text: (function(f){if(typeof exports==="object"&&typeof module!=="undefined"){module.exports=f()}else if(typeof define==="function"&&define.amd){define([],f)}else{var g;if(typeof window!=="undefined"){g=window}else if(typeof global!=="undefined"){g=global}else if(typeof self!=="undefined"){g=self}else{g=this}g.mqtt = f()}})(function(){var define,module,exports;return (function(){function r(e,n,t){function o(i,f){if(!n[i]){if(!e[i]){var c="function"==typeof require&&require;if(!f&&c)return c(i,!0);if(u)return u(i,!0);var a=new Error("Cannot find module '"+i+"'");throw a.code="MODULE_NOT_FOUND",a}var p=n[i]={exports:{}};e[i][0].call(p.exports,function(r){var n=e[i][1][r];return o(n||r)},p,p.exports,r,e,n,t)}return n[i].exports}for(var u="function"==typeof require&&require,i=0;i<t.length;i++)o(t[i]);return o}return r})()({1:[function(require,module,exports){
  (function (process,global){
  'use strict'
  
  /**
   * Module dependencies
   */
  var EventEmitter = require('events').EventEmitter
  var Store = require('./store')
  var mqttPacket = require('mqtt-packet')
  var Writable = require('readable-stream').Writable
  var inherits = require('inherits')
  var reInterval = require('reinterval')
  var validations = require('./validations')
  var xtend = require('xtend')
  var debug = require('debug')('mqttjs:client')
  var nextTick = process ? process.nextTick : function (callback) { setTimeout(callback, 0) }
  var setImmediate = global.setImmediate || function (callback) {
    // works in node v0.8
    nextTick(callback)
  }
  var defaultConnectOptions = {
    keepalive: 60,
    reschedulePings: true,
    protocolId: 'MQTT',
    protocolVersion: 4,
    reconnectPeriod: 1000,
    connectTimeout: 30 * 1000,
    clean: true,
    resubscribe: true
  }
  
  var socketErrors = [
    'ECONNREFUSED',
    'EADDRINUSE',
    'ECONNRESET',
    'ENOTFOUND'
  ]
  
  // Other Socket Errors: EADDRINUSE, ECONNRESET, ENOTFOUND.
  
  var errors = {
    0: '',
    1: 'Unacceptable protocol version',
    2: 'Identifier rejected',
    3: 'Server unavailable',
    4: 'Bad username or password',
    5: 'Not authorized',
    16: 'No matching subscribers',
    17: 'No subscription existed',
    128: 'Unspecified error',
    129: 'Malformed Packet',
    130: 'Protocol Error',
    131: 'Implementation specific error',
    132: 'Unsupported Protocol Version',
    133: 'Client Identifier not valid',
    134: 'Bad User Name or Password',
    135: 'Not authorized',
    136: 'Server unavailable',
    137: 'Server busy',
    138: 'Banned',
    139: 'Server shutting down',
    140: 'Bad authentication method',
    141: 'Keep Alive timeout',
    142: 'Session taken over',
    143: 'Topic Filter invalid',
    144: 'Topic Name invalid',
    145: 'Packet identifier in use',
    146: 'Packet Identifier not found',
    147: 'Receive Maximum exceeded',
    148: 'Topic Alias invalid',
    149: 'Packet too large',
    150: 'Message rate too high',
    151: 'Quota exceeded',
    152: 'Administrative action',
    153: 'Payload format invalid',
    154: 'Retain not supported',
    155: 'QoS not supported',
    156: 'Use another server',
    157: 'Server moved',
    158: 'Shared Subscriptions not supported',
    159: 'Connection rate exceeded',
    160: 'Maximum connect time',
    161: 'Subscription Identifiers not supported',
    162: 'Wildcard Subscriptions not supported'
  }
  
  function defaultId () {
    return 'mqttjs_' + Math.random().toString(16).substr(2, 8)
  }
  
  function sendPacket (client, packet, cb) {
    debug('sendPacket :: packet: %O', packet)
    debug('sendPacket :: emitting `packetsend`')
    client.emit('packetsend', packet)
  
    debug('sendPacket :: writing to stream')
    var result = mqttPacket.writeToStream(packet, client.stream, client.options)
    debug('sendPacket :: writeToStream result %s', result)
    if (!result && cb) {
      debug('sendPacket :: handle events on `drain` once through callback.')
      client.stream.once('drain', cb)
    } else if (cb) {
      debug('sendPacket :: invoking cb')
      cb()
    }
  }
  
  function flush (queue) {
    if (queue) {
      debug('flush: queue exists? %b', !!(queue))
      Object.keys(queue).forEach(function (messageId) {
        if (typeof queue[messageId].cb === 'function') {
          queue[messageId].cb(new Error('Connection closed'))
          delete queue[messageId]
        }
      })
    }
  }
  
  function flushVolatile (queue) {
    if (queue) {
      debug('flushVolatile :: deleting volatile messages from the queue and setting their callbacks as error function')
      Object.keys(queue).forEach(function (messageId) {
        if (queue[messageId].volatile && typeof queue[messageId].cb === 'function') {
          queue[messageId].cb(new Error('Connection closed'))
          delete queue[messageId]
        }
      })
    }
  }
  
  function storeAndSend (client, packet, cb, cbStorePut) {
    debug('storeAndSend :: store packet with cmd %s to outgoingStore', packet.cmd)
    client.outgoingStore.put(packet, function storedPacket (err) {
      if (err) {
        return cb && cb(err)
      }
      cbStorePut()
      sendPacket(client, packet, cb)
    })
  }
  
  function nop (error) {
    debug('nop ::', error)
  }
  
  /**
   * MqttClient constructor
   *
   * @param {Stream} stream - stream
   * @param {Object} [options] - connection options
   * (see Connection#connect)
   */
  function MqttClient (streamBuilder, options) {
    var k
    var that = this
  
    if (!(this instanceof MqttClient)) {
      return new MqttClient(streamBuilder, options)
    }
  
    this.options = options || {}
  
    // Defaults
    for (k in defaultConnectOptions) {
      if (typeof this.options[k] === 'undefined') {
        this.options[k] = defaultConnectOptions[k]
      } else {
        this.options[k] = options[k]
      }
    }
  
    debug('MqttClient :: options.protocol', options.protocol)
    debug('MqttClient :: options.protocolVersion', options.protocolVersion)
    debug('MqttClient :: options.username', options.username)
    debug('MqttClient :: options.keepalive', options.keepalive)
    debug('MqttClient :: options.reconnectPeriod', options.reconnectPeriod)
    debug('MqttClient :: options.rejectUnauthorized', options.rejectUnauthorized)
  
    this.options.clientId = (typeof options.clientId === 'string') ? options.clientId : defaultId()
  
    debug('MqttClient :: clientId', this.options.clientId)
  
    this.options.customHandleAcks = (options.protocolVersion === 5 && options.customHandleAcks) ? options.customHandleAcks : function () { arguments[3](0) }
  
    this.streamBuilder = streamBuilder
  
    // Inflight message storages
    this.outgoingStore = options.outgoingStore || new Store()
    this.incomingStore = options.incomingStore || new Store()
  
    // Should QoS zero messages be queued when the connection is broken?
    this.queueQoSZero = options.queueQoSZero === undefined ? true : options.queueQoSZero
  
    // map of subscribed topics to support reconnection
    this._resubscribeTopics = {}
  
    // map of a subscribe messageId and a topic
    this.messageIdToTopic = {}
  
    // Ping timer, setup in _setupPingTimer
    this.pingTimer = null
    // Is the client connected?
    this.connected = false
    // Are we disconnecting?
    this.disconnecting = false
    // Packet queue
    this.queue = []
    // connack timer
    this.connackTimer = null
    // Reconnect timer
    this.reconnectTimer = null
    // Is processing store?
    this._storeProcessing = false
    // Packet Ids are put into the store during store processing
    this._packetIdsDuringStoreProcessing = {}
    /**
     * MessageIDs starting with 1
     * ensure that nextId is min. 1, see https://github.com/mqttjs/MQTT.js/issues/810
     */
    this.nextId = Math.max(1, Math.floor(Math.random() * 65535))
  
    // Inflight callbacks
    this.outgoing = {}
  
    // True if connection is first time.
    this._firstConnection = true
  
    // Send queued packets
    this.on('connect', function () {
      var queue = this.queue
  
      function deliver () {
        var entry = queue.shift()
        debug('deliver :: entry %o', entry)
        var packet = null
  
        if (!entry) {
          return
        }
  
        packet = entry.packet
        debug('deliver :: call _sendPacket for %o', packet)
        that._sendPacket(
          packet,
          function (err) {
            if (entry.cb) {
              entry.cb(err)
            }
            deliver()
          }
        )
      }
  
      debug('connect :: sending queued packets')
      deliver()
    })
  
    this.on('close', function () {
      debug('close :: connected set to `false`')
      this.connected = false
  
      debug('close :: clearing connackTimer')
      clearTimeout(this.connackTimer)
  
      debug('close :: clearing ping timer')
      if (that.pingTimer !== null) {
        that.pingTimer.clear()
        that.pingTimer = null
      }
  
      debug('close :: calling _setupReconnect')
      this._setupReconnect()
    })
    EventEmitter.call(this)
  
    debug('MqttClient :: setting up stream')
    this._setupStream()
  }
  inherits(MqttClient, EventEmitter)
  
  /**
   * setup the event handlers in the inner stream.
   *
   * @api private
   */
  MqttClient.prototype._setupStream = function () {
    var connectPacket
    var that = this
    var writable = new Writable()
    var parser = mqttPacket.parser(this.options)
    var completeParse = null
    var packets = []
  
    debug('_setupStream :: calling method to clear reconnect')
    this._clearReconnect()
  
    debug('_setupStream :: using streamBuilder provided to client to create stream')
    this.stream = this.streamBuilder(this)
  
    parser.on('packet', function (packet) {
      debug('parser :: on packet push to packets array.')
      packets.push(packet)
    })
  
    function nextTickWork () {
      if (packets.length) {
        nextTick(work)
      } else {
        var done = completeParse
        completeParse = null
        done()
      }
    }
  
    function work () {
      debug('work :: getting next packet in queue')
      var packet = packets.shift()
  
      if (packet) {
        debug('work :: packet pulled from queue')
        that._handlePacket(packet, nextTickWork)
      } else {
        debug('work :: no packets in queue')
        var done = completeParse
        completeParse = null
        debug('work :: done flag is %s', !!(done))
        if (done) done()
      }
    }
  
    writable._write = function (buf, enc, done) {
      completeParse = done
      debug('writable stream :: parsing buffer')
      parser.parse(buf)
      work()
    }
  
    function streamErrorHandler (error) {
      debug('streamErrorHandler :: error', error.message)
      if (socketErrors.includes(error.code)) {
        // handle error
        debug('streamErrorHandler :: emitting error')
        that.emit('error', error)
      } else {
        nop(error)
      }
    }
  
    debug('_setupStream :: pipe stream to writable stream')
    this.stream.pipe(writable)
  
    // Suppress connection errors
    this.stream.on('error', streamErrorHandler)
  
    // Echo stream close
    this.stream.on('close', function () {
      debug('(%s)stream :: on close', that.options.clientId)
      flushVolatile(that.outgoing)
      debug('stream: emit close to MqttClient')
      that.emit('close')
    })
  
    // Send a connect packet
    debug('_setupStream: sending packet `connect`')
    connectPacket = Object.create(this.options)
    connectPacket.cmd = 'connect'
    // avoid message queue
    sendPacket(this, connectPacket)
  
    // Echo connection errors
    parser.on('error', this.emit.bind(this, 'error'))
  
    // auth
    if (this.options.properties) {
      if (!this.options.properties.authenticationMethod && this.options.properties.authenticationData) {
        that.end(() =>
          this.emit('error', new Error('Packet has no Authentication Method')
          ))
        return this
      }
      if (this.options.properties.authenticationMethod && this.options.authPacket && typeof this.options.authPacket === 'object') {
        var authPacket = xtend({cmd: 'auth', reasonCode: 0}, this.options.authPacket)
        sendPacket(this, authPacket)
      }
    }
  
    // many drain listeners are needed for qos 1 callbacks if the connection is intermittent
    this.stream.setMaxListeners(1000)
  
    clearTimeout(this.connackTimer)
    this.connackTimer = setTimeout(function () {
      debug('!!connectTimeout hit!! Calling _cleanUp with force `true`')
      that._cleanUp(true)
    }, this.options.connectTimeout)
  }
  
  MqttClient.prototype._handlePacket = function (packet, done) {
    var options = this.options
  
    if (options.protocolVersion === 5 && options.properties && options.properties.maximumPacketSize && options.properties.maximumPacketSize < packet.length) {
      this.emit('error', new Error('exceeding packets size ' + packet.cmd))
      this.end({reasonCode: 149, properties: { reasonString: 'Maximum packet size was exceeded' }})
      return this
    }
    debug('_handlePacket :: emitting packetreceive')
    this.emit('packetreceive', packet)
  
    switch (packet.cmd) {
      case 'publish':
        this._handlePublish(packet, done)
        break
      case 'puback':
      case 'pubrec':
      case 'pubcomp':
      case 'suback':
      case 'unsuback':
        this._handleAck(packet)
        done()
        break
      case 'pubrel':
        this._handlePubrel(packet, done)
        break
      case 'connack':
        this._handleConnack(packet)
        done()
        break
      case 'pingresp':
        this._handlePingresp(packet)
        done()
        break
      case 'disconnect':
        this._handleDisconnect(packet)
        done()
        break
      default:
        // do nothing
        // maybe we should do an error handling
        // or just log it
        break
    }
  }
  
  MqttClient.prototype._checkDisconnecting = function (callback) {
    if (this.disconnecting) {
      if (callback) {
        callback(new Error('client disconnecting'))
      } else {
        this.emit('error', new Error('client disconnecting'))
      }
    }
    return this.disconnecting
  }
  
  /**
   * publish - publish <message> to <topic>
   *
   * @param {String} topic - topic to publish to
   * @param {String, Buffer} message - message to publish
   * @param {Object} [opts] - publish options, includes:
   *    {Number} qos - qos level to publish on
   *    {Boolean} retain - whether or not to retain the message
   *    {Boolean} dup - whether or not mark a message as duplicate
   *    {Function} cbStorePut - function(){} called when message is put into `outgoingStore`
   * @param {Function} [callback] - function(err){}
   *    called when publish succeeds or fails
   * @returns {MqttClient} this - for chaining
   * @api public
   *
   * @example client.publish('topic', 'message');
   * @example
   *     client.publish('topic', 'message', {qos: 1, retain: true, dup: true});
   * @example client.publish('topic', 'message', console.log);
   */
  MqttClient.prototype.publish = function (topic, message, opts, callback) {
    debug('publish :: message `%s` to topic `%s`', message, topic)
    var packet
    var options = this.options
  
    // .publish(topic, payload, cb);
    if (typeof opts === 'function') {
      callback = opts
      opts = null
    }
  
    // default opts
    var defaultOpts = {qos: 0, retain: false, dup: false}
    opts = xtend(defaultOpts, opts)
  
    if (this._checkDisconnecting(callback)) {
      return this
    }
  
    packet = {
      cmd: 'publish',
      topic: topic,
      payload: message,
      qos: opts.qos,
      retain: opts.retain,
      messageId: this._nextId(),
      dup: opts.dup
    }
  
    if (options.protocolVersion === 5) {
      packet.properties = opts.properties
      if ((!options.properties && packet.properties && packet.properties.topicAlias) || ((opts.properties && options.properties) &&
        ((opts.properties.topicAlias && options.properties.topicAliasMaximum && opts.properties.topicAlias > options.properties.topicAliasMaximum) ||
          (!options.properties.topicAliasMaximum && opts.properties.topicAlias)))) {
        /*
        if we are don`t setup topic alias or
        topic alias maximum less than topic alias or
        server don`t give topic alias maximum,
        we are removing topic alias from packet
        */
        delete packet.properties.topicAlias
      }
    }
  
    debug('publish :: qos', opts.qos)
    switch (opts.qos) {
      case 1:
      case 2:
        // Add to callbacks
        this.outgoing[packet.messageId] = {
          volatile: false,
          cb: callback || nop
        }
        if (this._storeProcessing) {
          debug('_storeProcessing enabled')
          this._packetIdsDuringStoreProcessing[packet.messageId] = false
          this._storePacket(packet, undefined, opts.cbStorePut)
        } else {
          debug('MqttClient:publish: packet cmd: %s', packet.cmd)
          this._sendPacket(packet, undefined, opts.cbStorePut)
        }
        break
      default:
        if (this._storeProcessing) {
          debug('_storeProcessing enabled')
          this._storePacket(packet, callback, opts.cbStorePut)
        } else {
          debug('MqttClient:publish: packet cmd: %s', packet.cmd)
          this._sendPacket(packet, callback, opts.cbStorePut)
        }
        break
    }
  
    return this
  }
  
  /**
   * subscribe - subscribe to <topic>
   *
   * @param {String, Array, Object} topic - topic(s) to subscribe to, supports objects in the form {'topic': qos}
   * @param {Object} [opts] - optional subscription options, includes:
   *    {Number} qos - subscribe qos level
   * @param {Function} [callback] - function(err, granted){} where:
   *    {Error} err - subscription error (none at the moment!)
   *    {Array} granted - array of {topic: 't', qos: 0}
   * @returns {MqttClient} this - for chaining
   * @api public
   * @example client.subscribe('topic');
   * @example client.subscribe('topic', {qos: 1});
   * @example client.subscribe({'topic': {qos: 0}, 'topic2': {qos: 1}}, console.log);
   * @example client.subscribe('topic', console.log);
   */
  MqttClient.prototype.subscribe = function () {
    var packet
    var args = new Array(arguments.length)
    for (var i = 0; i < arguments.length; i++) {
      args[i] = arguments[i]
    }
    var subs = []
    var obj = args.shift()
    var resubscribe = obj.resubscribe
    var callback = args.pop() || nop
    var opts = args.pop()
    var invalidTopic
    var that = this
    var version = this.options.protocolVersion
  
    delete obj.resubscribe
  
    if (typeof obj === 'string') {
      obj = [obj]
    }
  
    if (typeof callback !== 'function') {
      opts = callback
      callback = nop
    }
  
    invalidTopic = validations.validateTopics(obj)
    if (invalidTopic !== null) {
      setImmediate(callback, new Error('Invalid topic ' + invalidTopic))
      return this
    }
  
    if (this._checkDisconnecting(callback)) {
      debug('subscribe: discconecting true')
      return this
    }
  
    var defaultOpts = {
      qos: 0
    }
    if (version === 5) {
      defaultOpts.nl = false
      defaultOpts.rap = false
      defaultOpts.rh = 0
    }
    opts = xtend(defaultOpts, opts)
  
    if (Array.isArray(obj)) {
      obj.forEach(function (topic) {
        debug('subscribe: array topic %s', topic)
        if (!that._resubscribeTopics.hasOwnProperty(topic) ||
          that._resubscribeTopics[topic].qos < opts.qos ||
            resubscribe) {
          var currentOpts = {
            topic: topic,
            qos: opts.qos
          }
          if (version === 5) {
            currentOpts.nl = opts.nl
            currentOpts.rap = opts.rap
            currentOpts.rh = opts.rh
            currentOpts.properties = opts.properties
          }
          debug('subscribe: pushing topic `%s` and qos `%s` to subs list', currentOpts.topic, currentOpts.qos)
          subs.push(currentOpts)
        }
      })
    } else {
      Object
        .keys(obj)
        .forEach(function (k) {
          debug('subscribe: object topic %s', k)
          if (!that._resubscribeTopics.hasOwnProperty(k) ||
            that._resubscribeTopics[k].qos < obj[k].qos ||
              resubscribe) {
            var currentOpts = {
              topic: k,
              qos: obj[k].qos
            }
            if (version === 5) {
              currentOpts.nl = obj[k].nl
              currentOpts.rap = obj[k].rap
              currentOpts.rh = obj[k].rh
              currentOpts.properties = opts.properties
            }
            debug('subscribe: pushing `%s` to subs list', currentOpts)
            subs.push(currentOpts)
          }
        })
    }
  
    packet = {
      cmd: 'subscribe',
      subscriptions: subs,
      qos: 1,
      retain: false,
      dup: false,
      messageId: this._nextId()
    }
  
    if (opts.properties) {
      packet.properties = opts.properties
    }
  
    if (!subs.length) {
      callback(null, [])
      return
    }
  
    // subscriptions to resubscribe to in case of disconnect
    if (this.options.resubscribe) {
      debug('subscribe :: resubscribe true')
      var topics = []
      subs.forEach(function (sub) {
        if (that.options.reconnectPeriod > 0) {
          var topic = { qos: sub.qos }
          if (version === 5) {
            topic.nl = sub.nl || false
            topic.rap = sub.rap || false
            topic.rh = sub.rh || 0
            topic.properties = sub.properties
          }
          that._resubscribeTopics[sub.topic] = topic
          topics.push(sub.topic)
        }
      })
      that.messageIdToTopic[packet.messageId] = topics
    }
  
    this.outgoing[packet.messageId] = {
      volatile: true,
      cb: function (err, packet) {
        if (!err) {
          var granted = packet.granted
          for (var i = 0; i < granted.length; i += 1) {
            subs[i].qos = granted[i]
          }
        }
  
        callback(err, subs)
      }
    }
    debug('subscribe :: call _sendPacket')
    this._sendPacket(packet)
  
    return this
  }
  
  /**
   * unsubscribe - unsubscribe from topic(s)
   *
   * @param {String, Array} topic - topics to unsubscribe from
   * @param {Object} [opts] - optional subscription options, includes:
   *    {Object} properties - properties of unsubscribe packet
   * @param {Function} [callback] - callback fired on unsuback
   * @returns {MqttClient} this - for chaining
   * @api public
   * @example client.unsubscribe('topic');
   * @example client.unsubscribe('topic', console.log);
   */
  MqttClient.prototype.unsubscribe = function () {
    var packet = {
      cmd: 'unsubscribe',
      qos: 1,
      messageId: this._nextId()
    }
    var that = this
    var args = new Array(arguments.length)
    for (var i = 0; i < arguments.length; i++) {
      args[i] = arguments[i]
    }
    var topic = args.shift()
    var callback = args.pop() || nop
    var opts = args.pop()
  
    if (typeof topic === 'string') {
      topic = [topic]
    }
  
    if (typeof callback !== 'function') {
      opts = callback
      callback = nop
    }
  
    if (this._checkDisconnecting(callback)) {
      return this
    }
  
    if (typeof topic === 'string') {
      packet.unsubscriptions = [topic]
    } else if (Array.isArray(topic)) {
      packet.unsubscriptions = topic
    }
  
    if (this.options.resubscribe) {
      packet.unsubscriptions.forEach(function (topic) {
        delete that._resubscribeTopics[topic]
      })
    }
  
    if (typeof opts === 'object' && opts.properties) {
      packet.properties = opts.properties
    }
  
    this.outgoing[packet.messageId] = {
      volatile: true,
      cb: callback
    }
  
    debug('unsubscribe: call _sendPacket')
    this._sendPacket(packet)
  
    return this
  }
  
  /**
   * end - close connection
   *
   * @returns {MqttClient} this - for chaining
   * @param {Boolean} force - do not wait for all in-flight messages to be acked
   * @param {Object} opts - added to the disconnect packet
   * @param {Function} cb - called when the client has been closed
   *
   * @api public
   */
  MqttClient.prototype.end = function (force, opts, cb) {
    var that = this
  
    debug('end :: (%s)', this.options.clientId)
  
    if (force == null || typeof force !== 'boolean') {
      cb = opts || nop
      opts = force
      force = false
      if (typeof opts !== 'object') {
        cb = opts
        opts = null
        if (typeof cb !== 'function') {
          cb = nop
        }
      }
    }
  
    if (typeof opts !== 'object') {
      cb = opts
      opts = null
    }
  
    debug('end :: cb? %s', !!cb)
    cb = cb || nop
  
    function closeStores () {
      debug('end :: closeStores: closing incoming and outgoing stores')
      that.disconnected = true
      that.incomingStore.close(function (e1) {
        that.outgoingStore.close(function (e2) {
          debug('end :: closeStores: emitting end')
          that.emit('end')
          if (cb) {
            let err = e1 || e2
            debug('end :: closeStores: invoking callback with args')
            cb(err)
          }
        })
      })
      if (that._deferredReconnect) {
        that._deferredReconnect()
      }
    }
  
    function finish () {
      // defer closesStores of an I/O cycle,
      // just to make sure things are
      // ok for websockets
      debug('end :: (%s) :: finish :: calling _cleanUp with force %s', that.options.clientId, force)
      that._cleanUp(force, () => {
        debug('end :: finish :: calling process.nextTick on closeStores')
        // var boundProcess = nextTick.bind(null, closeStores)
        nextTick(closeStores.bind(that))
      }, opts)
    }
  
    if (this.disconnecting) {
      cb()
      return this
    }
  
    this._clearReconnect()
  
    this.disconnecting = true
  
    if (!force && Object.keys(this.outgoing).length > 0) {
      // wait 10ms, just to be sure we received all of it
      debug('end :: (%s) :: calling finish in 10ms once outgoing is empty', that.options.clientId)
      this.once('outgoingEmpty', setTimeout.bind(null, finish, 10))
    } else {
      debug('end :: (%s) :: immediately calling finish', that.options.clientId)
      finish()
    }
  
    return this
  }
  
  /**
   * removeOutgoingMessage - remove a message in outgoing store
   * the outgoing callback will be called withe Error('Message removed') if the message is removed
   *
   * @param {Number} messageId - messageId to remove message
   * @returns {MqttClient} this - for chaining
   * @api public
   *
   * @example client.removeOutgoingMessage(client.getLastMessageId());
   */
  MqttClient.prototype.removeOutgoingMessage = function (messageId) {
    var cb = this.outgoing[messageId] ? this.outgoing[messageId].cb : null
    delete this.outgoing[messageId]
    this.outgoingStore.del({messageId: messageId}, function () {
      cb(new Error('Message removed'))
    })
    return this
  }
  
  /**
   * reconnect - connect again using the same options as connect()
   *
   * @param {Object} [opts] - optional reconnect options, includes:
   *    {Store} incomingStore - a store for the incoming packets
   *    {Store} outgoingStore - a store for the outgoing packets
   *    if opts is not given, current stores are used
   * @returns {MqttClient} this - for chaining
   *
   * @api public
   */
  MqttClient.prototype.reconnect = function (opts) {
    debug('client reconnect')
    var that = this
    var f = function () {
      if (opts) {
        that.options.incomingStore = opts.incomingStore
        that.options.outgoingStore = opts.outgoingStore
      } else {
        that.options.incomingStore = null
        that.options.outgoingStore = null
      }
      that.incomingStore = that.options.incomingStore || new Store()
      that.outgoingStore = that.options.outgoingStore || new Store()
      that.disconnecting = false
      that.disconnected = false
      that._deferredReconnect = null
      that._reconnect()
    }
  
    if (this.disconnecting && !this.disconnected) {
      this._deferredReconnect = f
    } else {
      f()
    }
    return this
  }
  
  /**
   * _reconnect - implement reconnection
   * @api privateish
   */
  MqttClient.prototype._reconnect = function () {
    debug('_reconnect: emitting reconnect to client')
    this.emit('reconnect')
    if (this.connected) {
      this.end(() => { this._setupStream() })
      debug('client already connected. disconnecting first.')
    } else {
      debug('_reconnect: calling _setupStream')
      this._setupStream()
    }
  }
  
  /**
   * _setupReconnect - setup reconnect timer
   */
  MqttClient.prototype._setupReconnect = function () {
    var that = this
  
    if (!that.disconnecting && !that.reconnectTimer && (that.options.reconnectPeriod > 0)) {
      if (!this.reconnecting) {
        debug('_setupReconnect :: emit `offline` state')
        this.emit('offline')
        debug('_setupReconnect :: set `reconnecting` to `true`')
        this.reconnecting = true
      }
      debug('_setupReconnect :: setting reconnectTimer for %d ms', that.options.reconnectPeriod)
      that.reconnectTimer = setInterval(function () {
        debug('reconnectTimer :: reconnect triggered!')
        that._reconnect()
      }, that.options.reconnectPeriod)
    } else {
      debug('_setupReconnect :: doing nothing...')
    }
  }
  
  /**
   * _clearReconnect - clear the reconnect timer
   */
  MqttClient.prototype._clearReconnect = function () {
    debug('_clearReconnect : clearing reconnect timer')
    if (this.reconnectTimer) {
      clearInterval(this.reconnectTimer)
      this.reconnectTimer = null
    }
  }
  
  /**
   * _cleanUp - clean up on connection end
   * @api private
   */
  MqttClient.prototype._cleanUp = function (forced, done) {
    var opts = arguments[2]
    if (done) {
      debug('_cleanUp :: done callback provided for on stream close')
      this.stream.on('close', done)
    }
  
    debug('_cleanUp :: forced? %s', forced)
    if (forced) {
      if ((this.options.reconnectPeriod === 0) && this.options.clean) {
        flush(this.outgoing)
      }
      debug('_cleanUp :: (%s) :: destroying stream', this.options.clientId)
      this.stream.destroy()
    } else {
      var packet = xtend({ cmd: 'disconnect' }, opts)
      debug('_cleanUp :: (%s) :: call _sendPacket with disconnect packet', this.options.clientId)
      this._sendPacket(
        packet,
        setImmediate.bind(
          null,
          this.stream.end.bind(this.stream)
        )
      )
    }
  
    if (!this.disconnecting) {
      debug('_cleanUp :: client not disconnecting. Clearing and resetting reconnect.')
      this._clearReconnect()
      this._setupReconnect()
    }
  
    if (this.pingTimer !== null) {
      debug('_cleanUp :: clearing pingTimer')
      this.pingTimer.clear()
      this.pingTimer = null
    }
  
    if (done && !this.connected) {
      debug('_cleanUp :: (%s) :: removing stream `done` callback `close` listener', this.options.clientId)
      this.stream.removeListener('close', done)
      done()
    }
  }
  
  /**
   * _sendPacket - send or queue a packet
   * @param {Object} packet - packet options
   * @param {Function} cb - callback when the packet is sent
   * @param {Function} cbStorePut - called when message is put into outgoingStore
   * @api private
   */
  MqttClient.prototype._sendPacket = function (packet, cb, cbStorePut) {
    debug('_sendPacket :: (%s) ::  start', this.options.clientId)
    cbStorePut = cbStorePut || nop
  
    if (!this.connected) {
      debug('_sendPacket :: client not connected. Storing packet offline.')
      this._storePacket(packet, cb, cbStorePut)
      return
    }
  
    // When sending a packet, reschedule the ping timer
    this._shiftPingInterval()
  
    switch (packet.cmd) {
      case 'publish':
        break
      case 'pubrel':
        storeAndSend(this, packet, cb, cbStorePut)
        return
      default:
        sendPacket(this, packet, cb)
        return
    }
  
    switch (packet.qos) {
      case 2:
      case 1:
        storeAndSend(this, packet, cb, cbStorePut)
        break
      /**
       * no need of case here since it will be caught by default
       * and jshint comply that before default it must be a break
       * anyway it will result in -1 evaluation
       */
      case 0:
        /* falls through */
      default:
        sendPacket(this, packet, cb)
        break
    }
    debug('_sendPacket :: (%s) ::  end', this.options.clientId)
  }
  
  /**
   * _storePacket - queue a packet
   * @param {Object} packet - packet options
   * @param {Function} cb - callback when the packet is sent
   * @param {Function} cbStorePut - called when message is put into outgoingStore
   * @api private
   */
  MqttClient.prototype._storePacket = function (packet, cb, cbStorePut) {
    debug('_storePacket :: packet: %o', packet)
    debug('_storePacket :: cb? %s', !!cb)
    cbStorePut = cbStorePut || nop
  
    // check that the packet is not a qos of 0, or that the command is not a publish
    if (((packet.qos || 0) === 0 && this.queueQoSZero) || packet.cmd !== 'publish') {
      this.queue.push({ packet: packet, cb: cb })
    } else if (packet.qos > 0) {
      cb = this.outgoing[packet.messageId] ? this.outgoing[packet.messageId].cb : null
      this.outgoingStore.put(packet, function (err) {
        if (err) {
          return cb && cb(err)
        }
        cbStorePut()
      })
    } else if (cb) {
      cb(new Error('No connection to broker'))
    }
  }
  
  /**
   * _setupPingTimer - setup the ping timer
   *
   * @api private
   */
  MqttClient.prototype._setupPingTimer = function () {
    debug('_setupPingTimer :: keepalive %d (seconds)', this.options.keepalive)
    var that = this
  
    if (!this.pingTimer && this.options.keepalive) {
      this.pingResp = true
      this.pingTimer = reInterval(function () {
        that._checkPing()
      }, this.options.keepalive * 1000)
    }
  }
  
  /**
   * _shiftPingInterval - reschedule the ping interval
   *
   * @api private
   */
  MqttClient.prototype._shiftPingInterval = function () {
    if (this.pingTimer && this.options.keepalive && this.options.reschedulePings) {
      this.pingTimer.reschedule(this.options.keepalive * 1000)
    }
  }
  /**
   * _checkPing - check if a pingresp has come back, and ping the server again
   *
   * @api private
   */
  MqttClient.prototype._checkPing = function () {
    debug('_checkPing :: checking ping...')
    if (this.pingResp) {
      debug('_checkPing :: ping response received. Clearing flag and sending `pingreq`')
      this.pingResp = false
      this._sendPacket({ cmd: 'pingreq' })
    } else {
      // do a forced cleanup since socket will be in bad shape
      debug('_checkPing :: calling _cleanUp with force true')
      this._cleanUp(true)
    }
  }
  
  /**
   * _handlePingresp - handle a pingresp
   *
   * @api private
   */
  MqttClient.prototype._handlePingresp = function () {
    this.pingResp = true
  }
  
  /**
   * _handleConnack
   *
   * @param {Object} packet
   * @api private
   */
  MqttClient.prototype._handleConnack = function (packet) {
    debug('_handleConnack')
    var options = this.options
    var version = options.protocolVersion
    var rc = version === 5 ? packet.reasonCode : packet.returnCode
  
    clearTimeout(this.connackTimer)
  
    if (packet.properties) {
      if (packet.properties.topicAliasMaximum) {
        if (!options.properties) { options.properties = {} }
        options.properties.topicAliasMaximum = packet.properties.topicAliasMaximum
      }
      if (packet.properties.serverKeepAlive && options.keepalive) {
        options.keepalive = packet.properties.serverKeepAlive
        this._shiftPingInterval()
      }
      if (packet.properties.maximumPacketSize) {
        if (!options.properties) { options.properties = {} }
        options.properties.maximumPacketSize = packet.properties.maximumPacketSize
      }
    }
  
    if (rc === 0) {
      this.reconnecting = false
      this._onConnect(packet)
    } else if (rc > 0) {
      var err = new Error('Connection refused: ' + errors[rc])
      err.code = rc
      this.emit('error', err)
    }
  }
  
  /**
   * _handlePublish
   *
   * @param {Object} packet
   * @api private
   */
  /*
  those late 2 case should be rewrite to comply with coding style:
  
  case 1:
  case 0:
    // do not wait sending a puback
    // no callback passed
    if (1 === qos) {
      this._sendPacket({
        cmd: 'puback',
        messageId: messageId
      });
    }
    // emit the message event for both qos 1 and 0
    this.emit('message', topic, message, packet);
    this.handleMessage(packet, done);
    break;
  default:
    // do nothing but every switch mus have a default
    // log or throw an error about unknown qos
    break;
  
  for now i just suppressed the warnings
  */
  MqttClient.prototype._handlePublish = function (packet, done) {
    debug('_handlePublish: packet %o', packet)
    done = typeof done !== 'undefined' ? done : nop
    var topic = packet.topic.toString()
    var message = packet.payload
    var qos = packet.qos
    var messageId = packet.messageId
    var that = this
    var options = this.options
    var validReasonCodes = [0, 16, 128, 131, 135, 144, 145, 151, 153]
    debug('_handlePublish: qos %d', qos)
    switch (qos) {
      case 2: {
        options.customHandleAcks(topic, message, packet, function (error, code) {
          if (!(error instanceof Error)) {
            code = error
            error = null
          }
          if (error) { return that.emit('error', error) }
          if (validReasonCodes.indexOf(code) === -1) { return that.emit('error', new Error('Wrong reason code for pubrec')) }
          if (code) {
            that._sendPacket({cmd: 'pubrec', messageId: messageId, reasonCode: code}, done)
          } else {
            that.incomingStore.put(packet, function () {
              that._sendPacket({cmd: 'pubrec', messageId: messageId}, done)
            })
          }
        })
        break
      }
      case 1: {
        // emit the message event
        options.customHandleAcks(topic, message, packet, function (error, code) {
          if (!(error instanceof Error)) {
            code = error
            error = null
          }
          if (error) { return that.emit('error', error) }
          if (validReasonCodes.indexOf(code) === -1) { return that.emit('error', new Error('Wrong reason code for puback')) }
          if (!code) { that.emit('message', topic, message, packet) }
          that.handleMessage(packet, function (err) {
            if (err) {
              return done && done(err)
            }
            that._sendPacket({cmd: 'puback', messageId: messageId, reasonCode: code}, done)
          })
        })
        break
      }
      case 0:
        // emit the message event
        this.emit('message', topic, message, packet)
        this.handleMessage(packet, done)
        break
      default:
        // do nothing
        debug('_handlePublish: unknown QoS. Doing nothing.')
        // log or throw an error about unknown qos
        break
    }
  }
  
  /**
   * Handle messages with backpressure support, one at a time.
   * Override at will.
   *
   * @param Packet packet the packet
   * @param Function callback call when finished
   * @api public
   */
  MqttClient.prototype.handleMessage = function (packet, callback) {
    callback()
  }
  
  /**
   * _handleAck
   *
   * @param {Object} packet
   * @api private
   */
  
  MqttClient.prototype._handleAck = function (packet) {
    /* eslint no-fallthrough: "off" */
    var messageId = packet.messageId
    var type = packet.cmd
    var response = null
    var cb = this.outgoing[messageId] ? this.outgoing[messageId].cb : null
    var that = this
    var err
  
    if (!cb) {
      debug('_handleAck :: Server sent an ack in error. Ignoring.')
      // Server sent an ack in error, ignore it.
      return
    }
  
    // Process
    debug('_handleAck :: packet type', type)
    switch (type) {
      case 'pubcomp':
        // same thing as puback for QoS 2
      case 'puback':
        var pubackRC = packet.reasonCode
        // Callback - we're done
        if (pubackRC && pubackRC > 0 && pubackRC !== 16) {
          err = new Error('Publish error: ' + errors[pubackRC])
          err.code = pubackRC
          cb(err, packet)
        }
        delete this.outgoing[messageId]
        this.outgoingStore.del(packet, cb)
        break
      case 'pubrec':
        response = {
          cmd: 'pubrel',
          qos: 2,
          messageId: messageId
        }
        var pubrecRC = packet.reasonCode
  
        if (pubrecRC && pubrecRC > 0 && pubrecRC !== 16) {
          err = new Error('Publish error: ' + errors[pubrecRC])
          err.code = pubrecRC
          cb(err, packet)
        } else {
          this._sendPacket(response)
        }
        break
      case 'suback':
        delete this.outgoing[messageId]
        for (var grantedI = 0; grantedI < packet.granted.length; grantedI++) {
          if ((packet.granted[grantedI] & 0x80) !== 0) {
            // suback with Failure status
            var topics = this.messageIdToTopic[messageId]
            if (topics) {
              topics.forEach(function (topic) {
                delete that._resubscribeTopics[topic]
              })
            }
          }
        }
        cb(null, packet)
        break
      case 'unsuback':
        delete this.outgoing[messageId]
        cb(null)
        break
      default:
        that.emit('error', new Error('unrecognized packet type'))
    }
  
    if (this.disconnecting &&
        Object.keys(this.outgoing).length === 0) {
      this.emit('outgoingEmpty')
    }
  }
  
  /**
   * _handlePubrel
   *
   * @param {Object} packet
   * @api private
   */
  MqttClient.prototype._handlePubrel = function (packet, callback) {
    debug('handling pubrel packet')
    callback = typeof callback !== 'undefined' ? callback : nop
    var messageId = packet.messageId
    var that = this
  
    var comp = {cmd: 'pubcomp', messageId: messageId}
  
    that.incomingStore.get(packet, function (err, pub) {
      if (!err) {
        that.emit('message', pub.topic, pub.payload, pub)
        that.handleMessage(pub, function (err) {
          if (err) {
            return callback(err)
          }
          that.incomingStore.del(pub, nop)
          that._sendPacket(comp, callback)
        })
      } else {
        that._sendPacket(comp, callback)
      }
    })
  }
  
  /**
   * _handleDisconnect
   *
   * @param {Object} packet
   * @api private
   */
  MqttClient.prototype._handleDisconnect = function (packet) {
    this.emit('disconnect', packet)
  }
  
  /**
   * _nextId
   * @return unsigned int
   */
  MqttClient.prototype._nextId = function () {
    // id becomes current state of this.nextId and increments afterwards
    var id = this.nextId++
    // Ensure 16 bit unsigned int (max 65535, nextId got one higher)
    if (this.nextId === 65536) {
      this.nextId = 1
    }
    return id
  }
  
  /**
   * getLastMessageId
   * @return unsigned int
   */
  MqttClient.prototype.getLastMessageId = function () {
    return (this.nextId === 1) ? 65535 : (this.nextId - 1)
  }
  
  /**
   * _resubscribe
   * @api private
   */
  MqttClient.prototype._resubscribe = function (connack) {
    debug('_resubscribe')
    var _resubscribeTopicsKeys = Object.keys(this._resubscribeTopics)
    if (!this._firstConnection &&
        (this.options.clean || (this.options.protocolVersion === 5 && !connack.sessionPresent)) &&
        _resubscribeTopicsKeys.length > 0) {
      if (this.options.resubscribe) {
        if (this.options.protocolVersion === 5) {
          debug('_resubscribe: protocolVersion 5')
          for (var topicI = 0; topicI < _resubscribeTopicsKeys.length; topicI++) {
            var resubscribeTopic = {}
            resubscribeTopic[_resubscribeTopicsKeys[topicI]] = this._resubscribeTopics[_resubscribeTopicsKeys[topicI]]
            resubscribeTopic.resubscribe = true
            this.subscribe(resubscribeTopic, {properties: resubscribeTopic[_resubscribeTopicsKeys[topicI]].properties})
          }
        } else {
          this._resubscribeTopics.resubscribe = true
          this.subscribe(this._resubscribeTopics)
        }
      } else {
        this._resubscribeTopics = {}
      }
    }
  
    this._firstConnection = false
  }
  
  /**
   * _onConnect
   *
   * @api private
   */
  MqttClient.prototype._onConnect = function (packet) {
    if (this.disconnected) {
      this.emit('connect', packet)
      return
    }
  
    var that = this
  
    this._setupPingTimer()
    this._resubscribe(packet)
  
    this.connected = true
  
    function startStreamProcess () {
      var outStore = that.outgoingStore.createStream()
  
      function clearStoreProcessing () {
        that._storeProcessing = false
        that._packetIdsDuringStoreProcessing = {}
      }
  
      that.once('close', remove)
      outStore.on('error', function (err) {
        clearStoreProcessing()
        that.removeListener('close', remove)
        that.emit('error', err)
      })
  
      function remove () {
        outStore.destroy()
        outStore = null
        clearStoreProcessing()
      }
  
      function storeDeliver () {
        // edge case, we wrapped this twice
        if (!outStore) {
          return
        }
        that._storeProcessing = true
  
        var packet = outStore.read(1)
  
        var cb
  
        if (!packet) {
          // read when data is available in the future
          outStore.once('readable', storeDeliver)
          return
        }
  
        // Skip already processed store packets
        if (that._packetIdsDuringStoreProcessing[packet.messageId]) {
          storeDeliver()
          return
        }
  
        // Avoid unnecessary stream read operations when disconnected
        if (!that.disconnecting && !that.reconnectTimer) {
          cb = that.outgoing[packet.messageId] ? that.outgoing[packet.messageId].cb : null
          that.outgoing[packet.messageId] = {
            volatile: false,
            cb: function (err, status) {
              // Ensure that the original callback passed in to publish gets invoked
              if (cb) {
                cb(err, status)
              }
  
              storeDeliver()
            }
          }
          that._packetIdsDuringStoreProcessing[packet.messageId] = true
          that._sendPacket(packet)
        } else if (outStore.destroy) {
          outStore.destroy()
        }
      }
  
      outStore.on('end', function () {
        var allProcessed = true
        for (var id in that._packetIdsDuringStoreProcessing) {
          if (!that._packetIdsDuringStoreProcessing[id]) {
            allProcessed = false
            break
          }
        }
        if (allProcessed) {
          clearStoreProcessing()
          that.removeListener('close', remove)
          that.emit('connect', packet)
        } else {
          startStreamProcess()
        }
      })
      storeDeliver()
    }
    // start flowing
    startStreamProcess()
  }
  
  module.exports = MqttClient
  
  }).call(this,require('_process'),typeof global !== "undefined" ? global : typeof self !== "undefined" ? self : typeof window !== "undefined" ? window : {})
  },{"./store":7,"./validations":8,"_process":44,"debug":14,"events":27,"inherits":29,"mqtt-packet":34,"readable-stream":59,"reinterval":60,"xtend":68}],2:[function(require,module,exports){
  (function (Buffer){
  'use strict'
  
  var Transform = require('readable-stream').Transform
  var duplexify = require('duplexify')
  
  /* global FileReader */
  var my
  var proxy
  var stream
  var isInitialized = false
  
  function buildProxy () {
    var proxy = new Transform()
    proxy._write = function (chunk, encoding, next) {
      my.sendSocketMessage({
        data: chunk.buffer,
        success: function () {
          next()
        },
        fail: function () {
          next(new Error())
        }
      })
    }
    proxy._flush = function socketEnd (done) {
      my.closeSocket({
        success: function () {
          done()
        }
      })
    }
  
    return proxy
  }
  
  function setDefaultOpts (opts) {
    if (!opts.hostname) {
      opts.hostname = 'localhost'
    }
    if (!opts.path) {
      opts.path = '/'
    }
  
    if (!opts.wsOptions) {
      opts.wsOptions = {}
    }
  }
  
  function buildUrl (opts, client) {
    var protocol = opts.protocol === 'alis' ? 'wss' : 'ws'
    var url = protocol + '://' + opts.hostname + opts.path
    if (opts.port && opts.port !== 80 && opts.port !== 443) {
      url = protocol + '://' + opts.hostname + ':' + opts.port + opts.path
    }
    if (typeof (opts.transformWsUrl) === 'function') {
      url = opts.transformWsUrl(url, opts, client)
    }
    return url
  }
  
  function bindEventHandler () {
    if (isInitialized) return
  
    isInitialized = true
  
    my.onSocketOpen(function () {
      stream.setReadable(proxy)
      stream.setWritable(proxy)
      stream.emit('connect')
    })
  
    my.onSocketMessage(function (res) {
      if (typeof res.data === 'string') {
        var buffer = Buffer.from(res.data, 'base64')
        proxy.push(buffer)
      } else {
        var reader = new FileReader()
        reader.addEventListener('load', function () {
          var data = reader.result
  
          if (data instanceof ArrayBuffer) data = Buffer.from(data)
          else data = Buffer.from(data, 'utf8')
          proxy.push(data)
        })
        reader.readAsArrayBuffer(res.data)
      }
    })
  
    my.onSocketClose(function () {
      stream.end()
      stream.destroy()
    })
  
    my.onSocketError(function (res) {
      stream.destroy(res)
    })
  }
  
  function buildStream (client, opts) {
    opts.hostname = opts.hostname || opts.host
  
    if (!opts.hostname) {
      throw new Error('Could not determine host. Specify host manually.')
    }
  
    var websocketSubProtocol =
      (opts.protocolId === 'MQIsdp') && (opts.protocolVersion === 3)
        ? 'mqttv3.1'
        : 'mqtt'
  
    setDefaultOpts(opts)
  
    var url = buildUrl(opts, client)
    my = opts.my
    my.connectSocket({
      url: url,
      protocols: websocketSubProtocol
    })
  
    proxy = buildProxy()
    stream = duplexify.obj()
  
    bindEventHandler()
  
    return stream
  }
  
  module.exports = buildStream
  
  }).call(this,require("buffer").Buffer)
  },{"buffer":12,"duplexify":16,"readable-stream":59}],3:[function(require,module,exports){
  'use strict'
  var net = require('net')
  var debug = require('debug')('mqttjs:tcp')
  
  /*
    variables port and host can be removed since
    you have all required information in opts object
  */
  function streamBuilder (client, opts) {
    var port, host
    opts.port = opts.port || 1883
    opts.hostname = opts.hostname || opts.host || 'localhost'
  
    port = opts.port
    host = opts.hostname
  
    debug('port %d and host %s', port, host)
    return net.createConnection(port, host)
  }
  
  module.exports = streamBuilder
  
  },{"debug":14,"net":11}],4:[function(require,module,exports){
  'use strict'
  var tls = require('tls')
  var debug = require('debug')('mqttjs:tls')
  
  function buildBuilder (mqttClient, opts) {
    var connection
    opts.port = opts.port || 8883
    opts.host = opts.hostname || opts.host || 'localhost'
    opts.servername = opts.host
  
    opts.rejectUnauthorized = opts.rejectUnauthorized !== false
  
    delete opts.path
  
    debug('port %d host %s rejectUnauthorized %b', opts.port, opts.host, opts.rejectUnauthorized)
  
    connection = tls.connect(opts)
    /* eslint no-use-before-define: [2, "nofunc"] */
    connection.on('secureConnect', function () {
      if (opts.rejectUnauthorized && !connection.authorized) {
        connection.emit('error', new Error('TLS not authorized'))
      } else {
        connection.removeListener('error', handleTLSerrors)
      }
    })
  
    function handleTLSerrors (err) {
      // How can I get verify this error is a tls error?
      if (opts.rejectUnauthorized) {
        mqttClient.emit('error', err)
      }
  
      // close this connection to match the behaviour of net
      // otherwise all we get is an error from the connection
      // and close event doesn't fire. This is a work around
      // to enable the reconnect code to work the same as with
      // net.createConnection
      connection.end()
    }
  
    connection.on('error', handleTLSerrors)
    return connection
  }
  
  module.exports = buildBuilder
  
  },{"debug":14,"tls":11}],5:[function(require,module,exports){
  (function (process,Buffer){
  'use strict'
  
  const WS = require('ws')
  const debug = require('debug')('mqttjs:ws')
  const duplexify = require('duplexify')
  const Transform = require('readable-stream').Transform
  
  let WSS_OPTIONS = [
    'rejectUnauthorized',
    'ca',
    'cert',
    'key',
    'pfx',
    'passphrase'
  ]
  // eslint-disable-next-line camelcase
  const IS_BROWSER = (typeof process !== 'undefined' && process.title === 'browser') || typeof __webpack_require__ === 'function'
  function buildUrl (opts, client) {
    let url = opts.protocol + '://' + opts.hostname + ':' + opts.port + opts.path
    if (typeof (opts.transformWsUrl) === 'function') {
      url = opts.transformWsUrl(url, opts, client)
    }
    return url
  }
  
  function setDefaultOpts (opts) {
    let options = opts
    if (!opts.hostname) {
      options.hostname = 'localhost'
    }
    if (!opts.port) {
      if (opts.protocol === 'wss') {
        options.port = 443
      } else {
        options.port = 80
      }
    }
    if (!opts.path) {
      options.path = '/'
    }
  
    if (!opts.wsOptions) {
      options.wsOptions = {}
    }
    if (!IS_BROWSER && opts.protocol === 'wss') {
      // Add cert/key/ca etc options
      WSS_OPTIONS.forEach(function (prop) {
        if (opts.hasOwnProperty(prop) && !opts.wsOptions.hasOwnProperty(prop)) {
          options.wsOptions[prop] = opts[prop]
        }
      })
    }
  
    return options
  }
  
  function setDefaultBrowserOpts (opts) {
    let options = setDefaultOpts(opts)
  
    if (!options.hostname) {
      options.hostname = options.host
    }
  
    if (!options.hostname) {
      // Throwing an error in a Web Worker if no `hostname` is given, because we
      // can not determine the `hostname` automatically.  If connecting to
      // localhost, please supply the `hostname` as an argument.
      if (typeof (document) === 'undefined') {
        throw new Error('Could not determine host. Specify host manually.')
      }
      const parsed = new URL(document.URL)
      options.hostname = parsed.hostname
  
      if (!options.port) {
        options.port = parsed.port
      }
    }
  
    // objectMode should be defined for logic
    if (options.objectMode === undefined) {
      options.objectMode = !(options.binary === true || options.binary === undefined)
    }
  
    return options
  }
  
  function createWebSocket (client, url, opts) {
    debug('createWebSocket')
    debug('protocol: ' + opts.protocolId + ' ' + opts.protocolVersion)
    const websocketSubProtocol =
      (opts.protocolId === 'MQIsdp') && (opts.protocolVersion === 3)
        ? 'mqttv3.1'
        : 'mqtt'
  
    debug('creating new Websocket for url: ' + url + ' and protocol: ' + websocketSubProtocol)
    let socket = new WS(url, [websocketSubProtocol], opts.wsOptions)
    return socket
  }
  
  function createBrowserWebSocket (client, opts) {
    const websocketSubProtocol =
    (opts.protocolId === 'MQIsdp') && (opts.protocolVersion === 3)
      ? 'mqttv3.1'
      : 'mqtt'
  
    let url = buildUrl(opts, client)
    /* global WebSocket */
    let socket = new WebSocket(url, [websocketSubProtocol])
    socket.binaryType = 'arraybuffer'
    return socket
  }
  
  function streamBuilder (client, opts) {
    debug('streamBuilder')
    let options = setDefaultOpts(opts)
    const url = buildUrl(options, client)
    let socket = createWebSocket(client, url, options)
    let webSocketStream = WS.createWebSocketStream(socket, options.wsOptions)
    webSocketStream.url = url
    return webSocketStream
  }
  
  function browserStreamBuilder (client, opts) {
    debug('browserStreamBuilder')
    let stream
    let options = setDefaultBrowserOpts(opts)
    // sets the maximum socket buffer size before throttling
    const bufferSize = options.browserBufferSize || 1024 * 512
  
    const bufferTimeout = opts.browserBufferTimeout || 1000
  
    const coerceToBuffer = !opts.objectMode
  
    let socket = createBrowserWebSocket(client, opts)
  
    let proxy = buildProxy(opts, socketWriteBrowser, socketEndBrowser)
  
    if (!opts.objectMode) {
      proxy._writev = writev
    }
    proxy.on('close', () => { socket.close() })
  
    const eventListenerSupport = (typeof socket.addEventListener === 'undefined')
  
    // was already open when passed in
    if (socket.readyState === socket.OPEN) {
      stream = proxy
    } else {
      stream = stream = duplexify(undefined, undefined, opts)
      if (!opts.objectMode) {
        stream._writev = writev
      }
  
      if (eventListenerSupport) {
        socket.addEventListener('open', onopen)
      } else {
        socket.onopen = onopen
      }
    }
  
    stream.socket = socket
  
    if (eventListenerSupport) {
      socket.addEventListener('close', onclose)
      socket.addEventListener('error', onerror)
      socket.addEventListener('message', onmessage)
    } else {
      socket.onclose = onclose
      socket.onerror = onerror
      socket.onmessage = onmessage
    }
  
    // methods for browserStreamBuilder
  
    function buildProxy (options, socketWrite, socketEnd) {
      let proxy = new Transform({
        objectModeMode: options.objectMode
      })
  
      proxy._write = socketWrite
      proxy._flush = socketEnd
  
      return proxy
    }
  
    function onopen () {
      stream.setReadable(proxy)
      stream.setWritable(proxy)
      stream.emit('connect')
    }
  
    function onclose () {
      stream.end()
      stream.destroy()
    }
  
    function onerror (err) {
      stream.destroy(err)
    }
  
    function onmessage (event) {
      let data = event.data
      if (data instanceof ArrayBuffer) data = Buffer.from(data)
      else data = Buffer.from(data, 'utf8')
      proxy.push(data)
    }
  
    // this is to be enabled only if objectMode is false
    function writev (chunks, cb) {
      const buffers = new Array(chunks.length)
      for (let i = 0; i < chunks.length; i++) {
        if (typeof chunks[i].chunk === 'string') {
          buffers[i] = Buffer.from(chunks[i], 'utf8')
        } else {
          buffers[i] = chunks[i].chunk
        }
      }
  
      this._write(Buffer.concat(buffers), 'binary', cb)
    }
  
    function socketWriteBrowser (chunk, enc, next) {
      if (socket.bufferedAmount > bufferSize) {
        // throttle data until buffered amount is reduced.
        setTimeout(socketWriteBrowser, bufferTimeout, chunk, enc, next)
      }
  
      if (coerceToBuffer && typeof chunk === 'string') {
        chunk = Buffer.from(chunk, 'utf8')
      }
  
      try {
        socket.send(chunk)
      } catch (err) {
        return next(err)
      }
  
      next()
    }
  
    function socketEndBrowser (done) {
      socket.close()
      done()
    }
  
    // end methods for browserStreamBuilder
  
    return stream
  }
  
  if (IS_BROWSER) {
    module.exports = browserStreamBuilder
  } else {
    module.exports = streamBuilder
  }
  
  }).call(this,require('_process'),require("buffer").Buffer)
  },{"_process":44,"buffer":12,"debug":14,"duplexify":16,"readable-stream":59,"ws":67}],6:[function(require,module,exports){
  (function (Buffer){
  'use strict'
  
  var Transform = require('readable-stream').Transform
  var duplexify = require('duplexify')
  
  /* global wx */
  var socketTask
  var proxy
  var stream
  
  function buildProxy () {
    var proxy = new Transform()
    proxy._write = function (chunk, encoding, next) {
      socketTask.send({
        data: chunk.buffer,
        success: function () {
          next()
        },
        fail: function (errMsg) {
          next(new Error(errMsg))
        }
      })
    }
    proxy._flush = function socketEnd (done) {
      socketTask.close({
        success: function () {
          done()
        }
      })
    }
  
    return proxy
  }
  
  function setDefaultOpts (opts) {
    if (!opts.hostname) {
      opts.hostname = 'localhost'
    }
    if (!opts.path) {
      opts.path = '/'
    }
  
    if (!opts.wsOptions) {
      opts.wsOptions = {}
    }
  }
  
  function buildUrl (opts, client) {
    var protocol = opts.protocol === 'wxs' ? 'wss' : 'ws'
    var url = protocol + '://' + opts.hostname + opts.path
    if (opts.port && opts.port !== 80 && opts.port !== 443) {
      url = protocol + '://' + opts.hostname + ':' + opts.port + opts.path
    }
    if (typeof (opts.transformWsUrl) === 'function') {
      url = opts.transformWsUrl(url, opts, client)
    }
    return url
  }
  
  function bindEventHandler () {
    socketTask.onOpen(function () {
      stream.setReadable(proxy)
      stream.setWritable(proxy)
      stream.emit('connect')
    })
  
    socketTask.onMessage(function (res) {
      var data = res.data
  
      if (data instanceof ArrayBuffer) data = Buffer.from(data)
      else data = Buffer.from(data, 'utf8')
      proxy.push(data)
    })
  
    socketTask.onClose(function () {
      stream.end()
      stream.destroy()
    })
  
    socketTask.onError(function (res) {
      stream.destroy(new Error(res.errMsg))
    })
  }
  
  function buildStream (client, opts) {
    opts.hostname = opts.hostname || opts.host
  
    if (!opts.hostname) {
      throw new Error('Could not determine host. Specify host manually.')
    }
  
    var websocketSubProtocol =
      (opts.protocolId === 'MQIsdp') && (opts.protocolVersion === 3)
        ? 'mqttv3.1'
        : 'mqtt'
  
    setDefaultOpts(opts)
  
    var url = buildUrl(opts, client)
    socketTask = wx.connectSocket({
      url: url,
      protocols: [websocketSubProtocol]
    })
  
    proxy = buildProxy()
    stream = duplexify.obj()
    stream._destroy = function (err, cb) {
      socketTask.close({
        success: function () {
          cb && cb(err)
        }
      })
    }
  
    var destroyRef = stream.destroy
    stream.destroy = function () {
      stream.destroy = destroyRef
  
      var self = this
      setTimeout(function () {
        socketTask.close({
          fail: function () {
            self._destroy(new Error())
          }
        })
      }, 0)
    }.bind(stream)
  
    bindEventHandler()
  
    return stream
  }
  
  module.exports = buildStream
  
  }).call(this,require("buffer").Buffer)
  },{"buffer":12,"duplexify":16,"readable-stream":59}],7:[function(require,module,exports){
  'use strict'
  
  /**
   * Module dependencies
   */
  var xtend = require('xtend')
  
  var Readable = require('readable-stream').Readable
  var streamsOpts = { objectMode: true }
  var defaultStoreOptions = {
    clean: true
  }
  
  /**
   * In-memory implementation of the message store
   * This can actually be saved into files.
   *
   * @param {Object} [options] - store options
   */
  function Store (options) {
    if (!(this instanceof Store)) {
      return new Store(options)
    }
  
    this.options = options || {}
  
    // Defaults
    this.options = xtend(defaultStoreOptions, options)
  
    this._inflights = new Map()
  }
  
  /**
   * Adds a packet to the store, a packet is
   * anything that has a messageId property.
   *
   */
  Store.prototype.put = function (packet, cb) {
    this._inflights.set(packet.messageId, packet)
  
    if (cb) {
      cb()
    }
  
    return this
  }
  
  /**
   * Creates a stream with all the packets in the store
   *
   */
  Store.prototype.createStream = function () {
    var stream = new Readable(streamsOpts)
    var destroyed = false
    var values = []
    var i = 0
  
    this._inflights.forEach(function (value, key) {
      values.push(value)
    })
  
    stream._read = function () {
      if (!destroyed && i < values.length) {
        this.push(values[i++])
      } else {
        this.push(null)
      }
    }
  
    stream.destroy = function () {
      if (destroyed) {
        return
      }
  
      var self = this
  
      destroyed = true
  
      setTimeout(function () {
        self.emit('close')
      }, 0)
    }
  
    return stream
  }
  
  /**
   * deletes a packet from the store.
   */
  Store.prototype.del = function (packet, cb) {
    packet = this._inflights.get(packet.messageId)
    if (packet) {
      this._inflights.delete(packet.messageId)
      cb(null, packet)
    } else if (cb) {
      cb(new Error('missing packet'))
    }
  
    return this
  }
  
  /**
   * get a packet from the store.
   */
  Store.prototype.get = function (packet, cb) {
    packet = this._inflights.get(packet.messageId)
    if (packet) {
      cb(null, packet)
    } else if (cb) {
      cb(new Error('missing packet'))
    }
  
    return this
  }
  
  /**
   * Close the store
   */
  Store.prototype.close = function (cb) {
    if (this.options.clean) {
      this._inflights = null
    }
    if (cb) {
      cb()
    }
  }
  
  module.exports = Store
  
  },{"readable-stream":59,"xtend":68}],8:[function(require,module,exports){
  'use strict'
  
  /**
   * Validate a topic to see if it's valid or not.
   * A topic is valid if it follow below rules:
   * - Rule #1: If any part of the topic is not `+` or `#`, then it must not contain `+` and '#'
   * - Rule #2: Part `#` must be located at the end of the mailbox
   *
   * @param {String} topic - A topic
   * @returns {Boolean} If the topic is valid, returns true. Otherwise, returns false.
   */
  function validateTopic (topic) {
    var parts = topic.split('/')
  
    for (var i = 0; i < parts.length; i++) {
      if (parts[i] === '+') {
        continue
      }
  
      if (parts[i] === '#') {
        // for Rule #2
        return i === parts.length - 1
      }
  
      if (parts[i].indexOf('+') !== -1 || parts[i].indexOf('#') !== -1) {
        return false
      }
    }
  
    return true
  }
  
  /**
   * Validate an array of topics to see if any of them is valid or not
    * @param {Array} topics - Array of topics
   * @returns {String} If the topics is valid, returns null. Otherwise, returns the invalid one
   */
  function validateTopics (topics) {
    if (topics.length === 0) {
      return 'empty_topic_list'
    }
    for (var i = 0; i < topics.length; i++) {
      if (!validateTopic(topics[i])) {
        return topics[i]
      }
    }
    return null
  }
  
  module.exports = {
    validateTopics: validateTopics
  }
  
  },{}],9:[function(require,module,exports){
  (function (process){
  'use strict'
  
  var MqttClient = require('../client')
  var Store = require('../store')
  var debug = require('debug')('mqttjs')
  
  var protocols = {}
  
  // eslint-disable-next-line camelcase
  if ((typeof process !== 'undefined' && process.title !== 'browser') || typeof __webpack_require__ !== 'function') {
    protocols.mqtt = require('./tcp')
    protocols.tcp = require('./tcp')
    protocols.ssl = require('./tls')
    protocols.tls = require('./tls')
    protocols.mqtts = require('./tls')
  } else {
    protocols.wx = require('./wx')
    protocols.wxs = require('./wx')
  
    protocols.ali = require('./ali')
    protocols.alis = require('./ali')
  }
  
  protocols.ws = require('./ws')
  protocols.wss = require('./ws')
  
  /**
   * Parse the auth attribute and merge username and password in the options object.
   *
   * @param {Object} [opts] option object
   */
  function parseAuthOptions (opts) {
    var matches
    if (opts.auth) {
      matches = opts.auth.match(/^(.+):(.+)$/)
      if (matches) {
        opts.username = matches[1]
        opts.password = matches[2]
      } else {
        opts.username = opts.auth
      }
    }
  }
  
  /**
   * connect - connect to an MQTT broker.
   *
   * @param {String} [brokerUrl] - url of the broker, optional
   * @param {Object} opts - see MqttClient#constructor
   */
  function connect (brokerUrl, opts) {
    debug('connecting to an MQTT broker...')
    if ((typeof brokerUrl === 'object') && !opts) {
      opts = brokerUrl
      brokerUrl = null
    }
  
    opts = opts || {}
  
    if (brokerUrl) {
      if (opts.protocol === null) {
        throw new Error('Missing protocol')
      }
      var parsed = new URL(brokerUrl)
  
      // the URL object is a bit special, so copy individual
      // items to the opts object
      opts.hash = parsed.hash
      opts.host = parsed.host
      opts.hostname = parsed.hostname
      opts.href = parsed.href
      opts.origin = parsed.origin
      opts.pathname = parsed.pathname
      opts.port = Number(parsed.port) || null
      opts.protocol = parsed.protocol
      opts.username = opts.username || parsed.username || null
      opts.password = opts.password || parsed.password || null
      opts.search = parsed.search
      opts.searchParams = parsed.searchParams
      opts.path = parsed.pathname + parsed.search
      opts.protocol = opts.protocol.replace(/:$/, '')
    }
  
    // merge in the auth options if supplied
    // legacy support for url.parse objects (now deprecated in node.js)
    parseAuthOptions(opts)
  
    // support clientId passed in the query string of the url
    if (opts.searchParams && typeof opts.searchParams.get('clientId') === 'string') {
      opts.clientId = opts.searchParams.get('clientId')
    }
  
    // legacy support for url.parse objects (now deprecated in node.js)
    if (opts.query && typeof opts.query.clientId === 'string') {
      opts.clientId = opts.query.clientId
    }
  
    if (opts.cert && opts.key) {
      if (opts.protocol) {
        if (['mqtts', 'wss', 'wxs', 'alis'].indexOf(opts.protocol) === -1) {
          switch (opts.protocol) {
            case 'mqtt':
              opts.protocol = 'mqtts'
              break
            case 'ws':
              opts.protocol = 'wss'
              break
            case 'wx':
              opts.protocol = 'wxs'
              break
            case 'ali':
              opts.protocol = 'alis'
              break
            default:
              throw new Error('Unknown protocol for secure connection: "' + opts.protocol + '"!')
          }
        }
      } else {
        // A cert and key was provided, however no protocol was specified, so we will throw an error.
        throw new Error('Missing secure protocol key')
      }
    }
  
    if (!protocols[opts.protocol]) {
      var isSecure = ['mqtts', 'wss'].indexOf(opts.protocol) !== -1
      opts.protocol = [
        'mqtt',
        'mqtts',
        'ws',
        'wss',
        'wx',
        'wxs',
        'ali',
        'alis'
      ].filter(function (key, index) {
        if (isSecure && index % 2 === 0) {
          // Skip insecure protocols when requesting a secure one.
          return false
        }
        return (typeof protocols[key] === 'function')
      })[0]
    }
  
    if (opts.clean === false && !opts.clientId) {
      throw new Error('Missing clientId for unclean clients')
    }
  
    if (opts.protocol) {
      opts.defaultProtocol = opts.protocol
    }
  
    function wrapper (client) {
      if (opts.servers) {
        if (!client._reconnectCount || client._reconnectCount === opts.servers.length) {
          client._reconnectCount = 0
        }
  
        opts.host = opts.servers[client._reconnectCount].host
        opts.port = opts.servers[client._reconnectCount].port
        opts.protocol = (!opts.servers[client._reconnectCount].protocol ? opts.defaultProtocol : opts.servers[client._reconnectCount].protocol)
        opts.hostname = opts.host
  
        client._reconnectCount++
      }
  
      debug('calling streambuilder for', opts.protocol)
      return protocols[opts.protocol](client, opts)
    }
    var client = new MqttClient(wrapper, opts)
    client.on('error', function () { /* Automatically set up client error handling */ })
    return client
  }
  
  module.exports = connect
  module.exports.connect = connect
  module.exports.MqttClient = MqttClient
  module.exports.Store = Store
  
  }).call(this,require('_process'))
  },{"../client":1,"../store":7,"./ali":2,"./tcp":3,"./tls":4,"./ws":5,"./wx":6,"_process":44,"debug":14}],10:[function(require,module,exports){
  'use strict'
  
  exports.byteLength = byteLength
  exports.toByteArray = toByteArray
  exports.fromByteArray = fromByteArray
  
  var lookup = []
  var revLookup = []
  var Arr = typeof Uint8Array !== 'undefined' ? Uint8Array : Array
  
  var code = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
  for (var i = 0, len = code.length; i < len; ++i) {
    lookup[i] = code[i]
    revLookup[code.charCodeAt(i)] = i
  }
  
  // Support decoding URL-safe base64 strings, as Node.js does.
  // See: https://en.wikipedia.org/wiki/Base64#URL_applications
  revLookup['-'.charCodeAt(0)] = 62
  revLookup['_'.charCodeAt(0)] = 63
  
  function getLens (b64) {
    var len = b64.length
  
    if (len % 4 > 0) {
      throw new Error('Invalid string. Length must be a multiple of 4')
    }
  
    // Trim off extra bytes after placeholder bytes are found
    // See: https://github.com/beatgammit/base64-js/issues/42
    var validLen = b64.indexOf('=')
    if (validLen === -1) validLen = len
  
    var placeHoldersLen = validLen === len
      ? 0
      : 4 - (validLen % 4)
  
    return [validLen, placeHoldersLen]
  }
  
  // base64 is 4/3 + up to two characters of the original data
  function byteLength (b64) {
    var lens = getLens(b64)
    var validLen = lens[0]
    var placeHoldersLen = lens[1]
    return ((validLen + placeHoldersLen) * 3 / 4) - placeHoldersLen
  }
  
  function _byteLength (b64, validLen, placeHoldersLen) {
    return ((validLen + placeHoldersLen) * 3 / 4) - placeHoldersLen
  }
  
  function toByteArray (b64) {
    var tmp
    var lens = getLens(b64)
    var validLen = lens[0]
    var placeHoldersLen = lens[1]
  
    var arr = new Arr(_byteLength(b64, validLen, placeHoldersLen))
  
    var curByte = 0
  
    // if there are placeholders, only get up to the last complete 4 chars
    var len = placeHoldersLen > 0
      ? validLen - 4
      : validLen
  
    var i
    for (i = 0; i < len; i += 4) {
      tmp =
        (revLookup[b64.charCodeAt(i)] << 18) |
        (revLookup[b64.charCodeAt(i + 1)] << 12) |
        (revLookup[b64.charCodeAt(i + 2)] << 6) |
        revLookup[b64.charCodeAt(i + 3)]
      arr[curByte++] = (tmp >> 16) & 0xFF
      arr[curByte++] = (tmp >> 8) & 0xFF
      arr[curByte++] = tmp & 0xFF
    }
  
    if (placeHoldersLen === 2) {
      tmp =
        (revLookup[b64.charCodeAt(i)] << 2) |
        (revLookup[b64.charCodeAt(i + 1)] >> 4)
      arr[curByte++] = tmp & 0xFF
    }
  
    if (placeHoldersLen === 1) {
      tmp =
        (revLookup[b64.charCodeAt(i)] << 10) |
        (revLookup[b64.charCodeAt(i + 1)] << 4) |
        (revLookup[b64.charCodeAt(i + 2)] >> 2)
      arr[curByte++] = (tmp >> 8) & 0xFF
      arr[curByte++] = tmp & 0xFF
    }
  
    return arr
  }
  
  function tripletToBase64 (num) {
    return lookup[num >> 18 & 0x3F] +
      lookup[num >> 12 & 0x3F] +
      lookup[num >> 6 & 0x3F] +
      lookup[num & 0x3F]
  }
  
  function encodeChunk (uint8, start, end) {
    var tmp
    var output = []
    for (var i = start; i < end; i += 3) {
      tmp =
        ((uint8[i] << 16) & 0xFF0000) +
        ((uint8[i + 1] << 8) & 0xFF00) +
        (uint8[i + 2] & 0xFF)
      output.push(tripletToBase64(tmp))
    }
    return output.join('')
  }
  
  function fromByteArray (uint8) {
    var tmp
    var len = uint8.length
    var extraBytes = len % 3 // if we have 1 byte left, pad 2 bytes
    var parts = []
    var maxChunkLength = 16383 // must be multiple of 3
  
    // go through the array every three bytes, we'll deal with trailing stuff later
    for (var i = 0, len2 = len - extraBytes; i < len2; i += maxChunkLength) {
      parts.push(encodeChunk(
        uint8, i, (i + maxChunkLength) > len2 ? len2 : (i + maxChunkLength)
      ))
    }
  
    // pad the end with zeros, but make sure to not forget the extra bytes
    if (extraBytes === 1) {
      tmp = uint8[len - 1]
      parts.push(
        lookup[tmp >> 2] +
        lookup[(tmp << 4) & 0x3F] +
        '=='
      )
    } else if (extraBytes === 2) {
      tmp = (uint8[len - 2] << 8) + uint8[len - 1]
      parts.push(
        lookup[tmp >> 10] +
        lookup[(tmp >> 4) & 0x3F] +
        lookup[(tmp << 2) & 0x3F] +
        '='
      )
    }
  
    return parts.join('')
  }
  
  },{}],11:[function(require,module,exports){
  
  },{}],12:[function(require,module,exports){
  (function (Buffer){
  /*!
   * The buffer module from node.js, for the browser.
   *
   * @author   Feross Aboukhadijeh <https://feross.org>
   * @license  MIT
   */
  /* eslint-disable no-proto */
  
  'use strict'
  
  var base64 = require('base64-js')
  var ieee754 = require('ieee754')
  
  exports.Buffer = Buffer
  exports.SlowBuffer = SlowBuffer
  exports.INSPECT_MAX_BYTES = 50
  
  var K_MAX_LENGTH = 0x7fffffff
  exports.kMaxLength = K_MAX_LENGTH
  
  /**
   * If `Buffer.TYPED_ARRAY_SUPPORT`:
   *   === true    Use Uint8Array implementation (fastest)
   *   === false   Print warning and recommend using `buffer` v4.x which has an Object
   *               implementation (most compatible, even IE6)
   *
   * Browsers that support typed arrays are IE 10+, Firefox 4+, Chrome 7+, Safari 5.1+,
   * Opera 11.6+, iOS 4.2+.
   *
   * We report that the browser does not support typed arrays if the are not subclassable
   * using __proto__. Firefox 4-29 lacks support for adding new properties to `Uint8Array`
   * (See: https://bugzilla.mozilla.org/show_bug.cgi?id=695438). IE 10 lacks support
   * for __proto__ and has a buggy typed array implementation.
   */
  Buffer.TYPED_ARRAY_SUPPORT = typedArraySupport()
  
  if (!Buffer.TYPED_ARRAY_SUPPORT && typeof console !== 'undefined' &&
      typeof console.error === 'function') {
    console.error(
      'This browser lacks typed array (Uint8Array) support which is required by ' +
      '`buffer` v5.x. Use `buffer` v4.x if you require old browser support.'
    )
  }
  
  function typedArraySupport () {
    // Can typed array instances can be augmented?
    try {
      var arr = new Uint8Array(1)
      arr.__proto__ = { __proto__: Uint8Array.prototype, foo: function () { return 42 } }
      return arr.foo() === 42
    } catch (e) {
      return false
    }
  }
  
  Object.defineProperty(Buffer.prototype, 'parent', {
    enumerable: true,
    get: function () {
      if (!Buffer.isBuffer(this)) return undefined
      return this.buffer
    }
  })
  
  Object.defineProperty(Buffer.prototype, 'offset', {
    enumerable: true,
    get: function () {
      if (!Buffer.isBuffer(this)) return undefined
      return this.byteOffset
    }
  })
  
  function createBuffer (length) {
    if (length > K_MAX_LENGTH) {
      throw new RangeError('The value "' + length + '" is invalid for option "size"')
    }
    // Return an augmented `Uint8Array` instance
    var buf = new Uint8Array(length)
    buf.__proto__ = Buffer.prototype
    return buf
  }
  
  /**
   * The Buffer constructor returns instances of `Uint8Array` that have their
   * prototype changed to `Buffer.prototype`. Furthermore, `Buffer` is a subclass of
   * `Uint8Array`, so the returned instances will have all the node `Buffer` methods
   * and the `Uint8Array` methods. Square bracket notation works as expected -- it
   * returns a single octet.
   *
   * The `Uint8Array` prototype remains unmodified.
   */
  
  function Buffer (arg, encodingOrOffset, length) {
    // Common case.
    if (typeof arg === 'number') {
      if (typeof encodingOrOffset === 'string') {
        throw new TypeError(
          'The "string" argument must be of type string. Received type number'
        )
      }
      return allocUnsafe(arg)
    }
    return from(arg, encodingOrOffset, length)
  }
  
  // Fix subarray() in ES2016. See: https://github.com/feross/buffer/pull/97
  if (typeof Symbol !== 'undefined' && Symbol.species != null &&
      Buffer[Symbol.species] === Buffer) {
    Object.defineProperty(Buffer, Symbol.species, {
      value: null,
      configurable: true,
      enumerable: false,
      writable: false
    })
  }
  
  Buffer.poolSize = 8192 // not used by this implementation
  
  function from (value, encodingOrOffset, length) {
    if (typeof value === 'string') {
      return fromString(value, encodingOrOffset)
    }
  
    if (ArrayBuffer.isView(value)) {
      return fromArrayLike(value)
    }
  
    if (value == null) {
      throw TypeError(
        'The first argument must be one of type string, Buffer, ArrayBuffer, Array, ' +
        'or Array-like Object. Received type ' + (typeof value)
      )
    }
  
    if (isInstance(value, ArrayBuffer) ||
        (value && isInstance(value.buffer, ArrayBuffer))) {
      return fromArrayBuffer(value, encodingOrOffset, length)
    }
  
    if (typeof value === 'number') {
      throw new TypeError(
        'The "value" argument must not be of type number. Received type number'
      )
    }
  
    var valueOf = value.valueOf && value.valueOf()
    if (valueOf != null && valueOf !== value) {
      return Buffer.from(valueOf, encodingOrOffset, length)
    }
  
    var b = fromObject(value)
    if (b) return b
  
    if (typeof Symbol !== 'undefined' && Symbol.toPrimitive != null &&
        typeof value[Symbol.toPrimitive] === 'function') {
      return Buffer.from(
        value[Symbol.toPrimitive]('string'), encodingOrOffset, length
      )
    }
  
    throw new TypeError(
      'The first argument must be one of type string, Buffer, ArrayBuffer, Array, ' +
      'or Array-like Object. Received type ' + (typeof value)
    )
  }
  
  /**
   * Functionally equivalent to Buffer(arg, encoding) but throws a TypeError
   * if value is a number.
   * Buffer.from(str[, encoding])
   * Buffer.from(array)
   * Buffer.from(buffer)
   * Buffer.from(arrayBuffer[, byteOffset[, length]])
   **/
  Buffer.from = function (value, encodingOrOffset, length) {
    return from(value, encodingOrOffset, length)
  }
  
  // Note: Change prototype *after* Buffer.from is defined to workaround Chrome bug:
  // https://github.com/feross/buffer/pull/148
  Buffer.prototype.__proto__ = Uint8Array.prototype
  Buffer.__proto__ = Uint8Array
  
  function assertSize (size) {
    if (typeof size !== 'number') {
      throw new TypeError('"size" argument must be of type number')
    } else if (size < 0) {
      throw new RangeError('The value "' + size + '" is invalid for option "size"')
    }
  }
  
  function alloc (size, fill, encoding) {
    assertSize(size)
    if (size <= 0) {
      return createBuffer(size)
    }
    if (fill !== undefined) {
      // Only pay attention to encoding if it's a string. This
      // prevents accidentally sending in a number that would
      // be interpretted as a start offset.
      return typeof encoding === 'string'
        ? createBuffer(size).fill(fill, encoding)
        : createBuffer(size).fill(fill)
    }
    return createBuffer(size)
  }
  
  /**
   * Creates a new filled Buffer instance.
   * alloc(size[, fill[, encoding]])
   **/
  Buffer.alloc = function (size, fill, encoding) {
    return alloc(size, fill, encoding)
  }
  
  function allocUnsafe (size) {
    assertSize(size)
    return createBuffer(size < 0 ? 0 : checked(size) | 0)
  }
  
  /**
   * Equivalent to Buffer(num), by default creates a non-zero-filled Buffer instance.
   * */
  Buffer.allocUnsafe = function (size) {
    return allocUnsafe(size)
  }
  /**
   * Equivalent to SlowBuffer(num), by default creates a non-zero-filled Buffer instance.
   */
  Buffer.allocUnsafeSlow = function (size) {
    return allocUnsafe(size)
  }
  
  function fromString (string, encoding) {
    if (typeof encoding !== 'string' || encoding === '') {
      encoding = 'utf8'
    }
  
    if (!Buffer.isEncoding(encoding)) {
      throw new TypeError('Unknown encoding: ' + encoding)
    }
  
    var length = byteLength(string, encoding) | 0
    var buf = createBuffer(length)
  
    var actual = buf.write(string, encoding)
  
    if (actual !== length) {
      // Writing a hex string, for example, that contains invalid characters will
      // cause everything after the first invalid character to be ignored. (e.g.
      // 'abxxcd' will be treated as 'ab')
      buf = buf.slice(0, actual)
    }
  
    return buf
  }
  
  function fromArrayLike (array) {
    var length = array.length < 0 ? 0 : checked(array.length) | 0
    var buf = createBuffer(length)
    for (var i = 0; i < length; i += 1) {
      buf[i] = array[i] & 255
    }
    return buf
  }
  
  function fromArrayBuffer (array, byteOffset, length) {
    if (byteOffset < 0 || array.byteLength < byteOffset) {
      throw new RangeError('"offset" is outside of buffer bounds')
    }
  
    if (array.byteLength < byteOffset + (length || 0)) {
      throw new RangeError('"length" is outside of buffer bounds')
    }
  
    var buf
    if (byteOffset === undefined && length === undefined) {
      buf = new Uint8Array(array)
    } else if (length === undefined) {
      buf = new Uint8Array(array, byteOffset)
    } else {
      buf = new Uint8Array(array, byteOffset, length)
    }
  
    // Return an augmented `Uint8Array` instance
    buf.__proto__ = Buffer.prototype
    return buf
  }
  
  function fromObject (obj) {
    if (Buffer.isBuffer(obj)) {
      var len = checked(obj.length) | 0
      var buf = createBuffer(len)
  
      if (buf.length === 0) {
        return buf
      }
  
      obj.copy(buf, 0, 0, len)
      return buf
    }
  
    if (obj.length !== undefined) {
      if (typeof obj.length !== 'number' || numberIsNaN(obj.length)) {
        return createBuffer(0)
      }
      return fromArrayLike(obj)
    }
  
    if (obj.type === 'Buffer' && Array.isArray(obj.data)) {
      return fromArrayLike(obj.data)
    }
  }
  
  function checked (length) {
    // Note: cannot use `length < K_MAX_LENGTH` here because that fails when
    // length is NaN (which is otherwise coerced to zero.)
    if (length >= K_MAX_LENGTH) {
      throw new RangeError('Attempt to allocate Buffer larger than maximum ' +
                           'size: 0x' + K_MAX_LENGTH.toString(16) + ' bytes')
    }
    return length | 0
  }
  
  function SlowBuffer (length) {
    if (+length != length) { // eslint-disable-line eqeqeq
      length = 0
    }
    return Buffer.alloc(+length)
  }
  
  Buffer.isBuffer = function isBuffer (b) {
    return b != null && b._isBuffer === true &&
      b !== Buffer.prototype // so Buffer.isBuffer(Buffer.prototype) will be false
  }
  
  Buffer.compare = function compare (a, b) {
    if (isInstance(a, Uint8Array)) a = Buffer.from(a, a.offset, a.byteLength)
    if (isInstance(b, Uint8Array)) b = Buffer.from(b, b.offset, b.byteLength)
    if (!Buffer.isBuffer(a) || !Buffer.isBuffer(b)) {
      throw new TypeError(
        'The "buf1", "buf2" arguments must be one of type Buffer or Uint8Array'
      )
    }
  
    if (a === b) return 0
  
    var x = a.length
    var y = b.length
  
    for (var i = 0, len = Math.min(x, y); i < len; ++i) {
      if (a[i] !== b[i]) {
        x = a[i]
        y = b[i]
        break
      }
    }
  
    if (x < y) return -1
    if (y < x) return 1
    return 0
  }
  
  Buffer.isEncoding = function isEncoding (encoding) {
    switch (String(encoding).toLowerCase()) {
      case 'hex':
      case 'utf8':
      case 'utf-8':
      case 'ascii':
      case 'latin1':
      case 'binary':
      case 'base64':
      case 'ucs2':
      case 'ucs-2':
      case 'utf16le':
      case 'utf-16le':
        return true
      default:
        return false
    }
  }
  
  Buffer.concat = function concat (list, length) {
    if (!Array.isArray(list)) {
      throw new TypeError('"list" argument must be an Array of Buffers')
    }
  
    if (list.length === 0) {
      return Buffer.alloc(0)
    }
  
    var i
    if (length === undefined) {
      length = 0
      for (i = 0; i < list.length; ++i) {
        length += list[i].length
      }
    }
  
    var buffer = Buffer.allocUnsafe(length)
    var pos = 0
    for (i = 0; i < list.length; ++i) {
      var buf = list[i]
      if (isInstance(buf, Uint8Array)) {
        buf = Buffer.from(buf)
      }
      if (!Buffer.isBuffer(buf)) {
        throw new TypeError('"list" argument must be an Array of Buffers')
      }
      buf.copy(buffer, pos)
      pos += buf.length
    }
    return buffer
  }
  
  function byteLength (string, encoding) {
    if (Buffer.isBuffer(string)) {
      return string.length
    }
    if (ArrayBuffer.isView(string) || isInstance(string, ArrayBuffer)) {
      return string.byteLength
    }
    if (typeof string !== 'string') {
      throw new TypeError(
        'The "string" argument must be one of type string, Buffer, or ArrayBuffer. ' +
        'Received type ' + typeof string
      )
    }
  
    var len = string.length
    var mustMatch = (arguments.length > 2 && arguments[2] === true)
    if (!mustMatch && len === 0) return 0
  
    // Use a for loop to avoid recursion
    var loweredCase = false
    for (;;) {
      switch (encoding) {
        case 'ascii':
        case 'latin1':
        case 'binary':
          return len
        case 'utf8':
        case 'utf-8':
          return utf8ToBytes(string).length
        case 'ucs2':
        case 'ucs-2':
        case 'utf16le':
        case 'utf-16le':
          return len * 2
        case 'hex':
          return len >>> 1
        case 'base64':
          return base64ToBytes(string).length
        default:
          if (loweredCase) {
            return mustMatch ? -1 : utf8ToBytes(string).length // assume utf8
          }
          encoding = ('' + encoding).toLowerCase()
          loweredCase = true
      }
    }
  }
  Buffer.byteLength = byteLength
  
  function slowToString (encoding, start, end) {
    var loweredCase = false
  
    // No need to verify that "this.length <= MAX_UINT32" since it's a read-only
    // property of a typed array.
  
    // This behaves neither like String nor Uint8Array in that we set start/end
    // to their upper/lower bounds if the value passed is out of range.
    // undefined is handled specially as per ECMA-262 6th Edition,
    // Section 13.3.3.7 Runtime Semantics: KeyedBindingInitialization.
    if (start === undefined || start < 0) {
      start = 0
    }
    // Return early if start > this.length. Done here to prevent potential uint32
    // coercion fail below.
    if (start > this.length) {
      return ''
    }
  
    if (end === undefined || end > this.length) {
      end = this.length
    }
  
    if (end <= 0) {
      return ''
    }
  
    // Force coersion to uint32. This will also coerce falsey/NaN values to 0.
    end >>>= 0
    start >>>= 0
  
    if (end <= start) {
      return ''
    }
  
    if (!encoding) encoding = 'utf8'
  
    while (true) {
      switch (encoding) {
        case 'hex':
          return hexSlice(this, start, end)
  
        case 'utf8':
        case 'utf-8':
          return utf8Slice(this, start, end)
  
        case 'ascii':
          return asciiSlice(this, start, end)
  
        case 'latin1':
        case 'binary':
          return latin1Slice(this, start, end)
  
        case 'base64':
          return base64Slice(this, start, end)
  
        case 'ucs2':
        case 'ucs-2':
        case 'utf16le':
        case 'utf-16le':
          return utf16leSlice(this, start, end)
  
        default:
          if (loweredCase) throw new TypeError('Unknown encoding: ' + encoding)
          encoding = (encoding + '').toLowerCase()
          loweredCase = true
      }
    }
  }
  
  // This property is used by `Buffer.isBuffer` (and the `is-buffer` npm package)
  // to detect a Buffer instance. It's not possible to use `instanceof Buffer`
  // reliably in a browserify context because there could be multiple different
  // copies of the 'buffer' package in use. This method works even for Buffer
  // instances that were created from another copy of the `buffer` package.
  // See: https://github.com/feross/buffer/issues/154
  Buffer.prototype._isBuffer = true
  
  function swap (b, n, m) {
    var i = b[n]
    b[n] = b[m]
    b[m] = i
  }
  
  Buffer.prototype.swap16 = function swap16 () {
    var len = this.length
    if (len % 2 !== 0) {
      throw new RangeError('Buffer size must be a multiple of 16-bits')
    }
    for (var i = 0; i < len; i += 2) {
      swap(this, i, i + 1)
    }
    return this
  }
  
  Buffer.prototype.swap32 = function swap32 () {
    var len = this.length
    if (len % 4 !== 0) {
      throw new RangeError('Buffer size must be a multiple of 32-bits')
    }
    for (var i = 0; i < len; i += 4) {
      swap(this, i, i + 3)
      swap(this, i + 1, i + 2)
    }
    return this
  }
  
  Buffer.prototype.swap64 = function swap64 () {
    var len = this.length
    if (len % 8 !== 0) {
      throw new RangeError('Buffer size must be a multiple of 64-bits')
    }
    for (var i = 0; i < len; i += 8) {
      swap(this, i, i + 7)
      swap(this, i + 1, i + 6)
      swap(this, i + 2, i + 5)
      swap(this, i + 3, i + 4)
    }
    return this
  }
  
  Buffer.prototype.toString = function toString () {
    var length = this.length
    if (length === 0) return ''
    if (arguments.length === 0) return utf8Slice(this, 0, length)
    return slowToString.apply(this, arguments)
  }
  
  Buffer.prototype.toLocaleString = Buffer.prototype.toString
  
  Buffer.prototype.equals = function equals (b) {
    if (!Buffer.isBuffer(b)) throw new TypeError('Argument must be a Buffer')
    if (this === b) return true
    return Buffer.compare(this, b) === 0
  }
  
  Buffer.prototype.inspect = function inspect () {
    var str = ''
    var max = exports.INSPECT_MAX_BYTES
    str = this.toString('hex', 0, max).replace(/(.{2})/g, '$1 ').trim()
    if (this.length > max) str += ' ... '
    return '<Buffer ' + str + '>'
  }
  
  Buffer.prototype.compare = function compare (target, start, end, thisStart, thisEnd) {
    if (isInstance(target, Uint8Array)) {
      target = Buffer.from(target, target.offset, target.byteLength)
    }
    if (!Buffer.isBuffer(target)) {
      throw new TypeError(
        'The "target" argument must be one of type Buffer or Uint8Array. ' +
        'Received type ' + (typeof target)
      )
    }
  
    if (start === undefined) {
      start = 0
    }
    if (end === undefined) {
      end = target ? target.length : 0
    }
    if (thisStart === undefined) {
      thisStart = 0
    }
    if (thisEnd === undefined) {
      thisEnd = this.length
    }
  
    if (start < 0 || end > target.length || thisStart < 0 || thisEnd > this.length) {
      throw new RangeError('out of range index')
    }
  
    if (thisStart >= thisEnd && start >= end) {
      return 0
    }
    if (thisStart >= thisEnd) {
      return -1
    }
    if (start >= end) {
      return 1
    }
  
    start >>>= 0
    end >>>= 0
    thisStart >>>= 0
    thisEnd >>>= 0
  
    if (this === target) return 0
  
    var x = thisEnd - thisStart
    var y = end - start
    var len = Math.min(x, y)
  
    var thisCopy = this.slice(thisStart, thisEnd)
    var targetCopy = target.slice(start, end)
  
    for (var i = 0; i < len; ++i) {
      if (thisCopy[i] !== targetCopy[i]) {
        x = thisCopy[i]
        y = targetCopy[i]
        break
      }
    }
  
    if (x < y) return -1
    if (y < x) return 1
    return 0
  }
  
  // Finds either the first index of `val` in `buffer` at offset >= `byteOffset`,
  // OR the last index of `val` in `buffer` at offset <= `byteOffset`.
  //
  // Arguments:
  // - buffer - a Buffer to search
  // - val - a string, Buffer, or number
  // - byteOffset - an index into `buffer`; will be clamped to an int32
  // - encoding - an optional encoding, relevant is val is a string
  // - dir - true for indexOf, false for lastIndexOf
  function bidirectionalIndexOf (buffer, val, byteOffset, encoding, dir) {
    // Empty buffer means no match
    if (buffer.length === 0) return -1
  
    // Normalize byteOffset
    if (typeof byteOffset === 'string') {
      encoding = byteOffset
      byteOffset = 0
    } else if (byteOffset > 0x7fffffff) {
      byteOffset = 0x7fffffff
    } else if (byteOffset < -0x80000000) {
      byteOffset = -0x80000000
    }
    byteOffset = +byteOffset // Coerce to Number.
    if (numberIsNaN(byteOffset)) {
      // byteOffset: it it's undefined, null, NaN, "foo", etc, search whole buffer
      byteOffset = dir ? 0 : (buffer.length - 1)
    }
  
    // Normalize byteOffset: negative offsets start from the end of the buffer
    if (byteOffset < 0) byteOffset = buffer.length + byteOffset
    if (byteOffset >= buffer.length) {
      if (dir) return -1
      else byteOffset = buffer.length - 1
    } else if (byteOffset < 0) {
      if (dir) byteOffset = 0
      else return -1
    }
  
    // Normalize val
    if (typeof val === 'string') {
      val = Buffer.from(val, encoding)
    }
  
    // Finally, search either indexOf (if dir is true) or lastIndexOf
    if (Buffer.isBuffer(val)) {
      // Special case: looking for empty string/buffer always fails
      if (val.length === 0) {
        return -1
      }
      return arrayIndexOf(buffer, val, byteOffset, encoding, dir)
    } else if (typeof val === 'number') {
      val = val & 0xFF // Search for a byte value [0-255]
      if (typeof Uint8Array.prototype.indexOf === 'function') {
        if (dir) {
          return Uint8Array.prototype.indexOf.call(buffer, val, byteOffset)
        } else {
          return Uint8Array.prototype.lastIndexOf.call(buffer, val, byteOffset)
        }
      }
      return arrayIndexOf(buffer, [ val ], byteOffset, encoding, dir)
    }
  
    throw new TypeError('val must be string, number or Buffer')
  }
  
  function arrayIndexOf (arr, val, byteOffset, encoding, dir) {
    var indexSize = 1
    var arrLength = arr.length
    var valLength = val.length
  
    if (encoding !== undefined) {
      encoding = String(encoding).toLowerCase()
      if (encoding === 'ucs2' || encoding === 'ucs-2' ||
          encoding === 'utf16le' || encoding === 'utf-16le') {
        if (arr.length < 2 || val.length < 2) {
          return -1
        }
        indexSize = 2
        arrLength /= 2
        valLength /= 2
        byteOffset /= 2
      }
    }
  
    function read (buf, i) {
      if (indexSize === 1) {
        return buf[i]
      } else {
        return buf.readUInt16BE(i * indexSize)
      }
    }
  
    var i
    if (dir) {
      var foundIndex = -1
      for (i = byteOffset; i < arrLength; i++) {
        if (read(arr, i) === read(val, foundIndex === -1 ? 0 : i - foundIndex)) {
          if (foundIndex === -1) foundIndex = i
          if (i - foundIndex + 1 === valLength) return foundIndex * indexSize
        } else {
          if (foundIndex !== -1) i -= i - foundIndex
          foundIndex = -1
        }
      }
    } else {
      if (byteOffset + valLength > arrLength) byteOffset = arrLength - valLength
      for (i = byteOffset; i >= 0; i--) {
        var found = true
        for (var j = 0; j < valLength; j++) {
          if (read(arr, i + j) !== read(val, j)) {
            found = false
            break
          }
        }
        if (found) return i
      }
    }
  
    return -1
  }
  
  Buffer.prototype.includes = function includes (val, byteOffset, encoding) {
    return this.indexOf(val, byteOffset, encoding) !== -1
  }
  
  Buffer.prototype.indexOf = function indexOf (val, byteOffset, encoding) {
    return bidirectionalIndexOf(this, val, byteOffset, encoding, true)
  }
  
  Buffer.prototype.lastIndexOf = function lastIndexOf (val, byteOffset, encoding) {
    return bidirectionalIndexOf(this, val, byteOffset, encoding, false)
  }
  
  function hexWrite (buf, string, offset, length) {
    offset = Number(offset) || 0
    var remaining = buf.length - offset
    if (!length) {
      length = remaining
    } else {
      length = Number(length)
      if (length > remaining) {
        length = remaining
      }
    }
  
    var strLen = string.length
  
    if (length > strLen / 2) {
      length = strLen / 2
    }
    for (var i = 0; i < length; ++i) {
      var parsed = parseInt(string.substr(i * 2, 2), 16)
      if (numberIsNaN(parsed)) return i
      buf[offset + i] = parsed
    }
    return i
  }
  
  function utf8Write (buf, string, offset, length) {
    return blitBuffer(utf8ToBytes(string, buf.length - offset), buf, offset, length)
  }
  
  function asciiWrite (buf, string, offset, length) {
    return blitBuffer(asciiToBytes(string), buf, offset, length)
  }
  
  function latin1Write (buf, string, offset, length) {
    return asciiWrite(buf, string, offset, length)
  }
  
  function base64Write (buf, string, offset, length) {
    return blitBuffer(base64ToBytes(string), buf, offset, length)
  }
  
  function ucs2Write (buf, string, offset, length) {
    return blitBuffer(utf16leToBytes(string, buf.length - offset), buf, offset, length)
  }
  
  Buffer.prototype.write = function write (string, offset, length, encoding) {
    // Buffer#write(string)
    if (offset === undefined) {
      encoding = 'utf8'
      length = this.length
      offset = 0
    // Buffer#write(string, encoding)
    } else if (length === undefined && typeof offset === 'string') {
      encoding = offset
      length = this.length
      offset = 0
    // Buffer#write(string, offset[, length][, encoding])
    } else if (isFinite(offset)) {
      offset = offset >>> 0
      if (isFinite(length)) {
        length = length >>> 0
        if (encoding === undefined) encoding = 'utf8'
      } else {
        encoding = length
        length = undefined
      }
    } else {
      throw new Error(
        'Buffer.write(string, encoding, offset[, length]) is no longer supported'
      )
    }
  
    var remaining = this.length - offset
    if (length === undefined || length > remaining) length = remaining
  
    if ((string.length > 0 && (length < 0 || offset < 0)) || offset > this.length) {
      throw new RangeError('Attempt to write outside buffer bounds')
    }
  
    if (!encoding) encoding = 'utf8'
  
    var loweredCase = false
    for (;;) {
      switch (encoding) {
        case 'hex':
          return hexWrite(this, string, offset, length)
  
        case 'utf8':
        case 'utf-8':
          return utf8Write(this, string, offset, length)
  
        case 'ascii':
          return asciiWrite(this, string, offset, length)
  
        case 'latin1':
        case 'binary':
          return latin1Write(this, string, offset, length)
  
        case 'base64':
          // Warning: maxLength not taken into account in base64Write
          return base64Write(this, string, offset, length)
  
        case 'ucs2':
        case 'ucs-2':
        case 'utf16le':
        case 'utf-16le':
          return ucs2Write(this, string, offset, length)
  
        default:
          if (loweredCase) throw new TypeError('Unknown encoding: ' + encoding)
          encoding = ('' + encoding).toLowerCase()
          loweredCase = true
      }
    }
  }
  
  Buffer.prototype.toJSON = function toJSON () {
    return {
      type: 'Buffer',
      data: Array.prototype.slice.call(this._arr || this, 0)
    }
  }
  
  function base64Slice (buf, start, end) {
    if (start === 0 && end === buf.length) {
      return base64.fromByteArray(buf)
    } else {
      return base64.fromByteArray(buf.slice(start, end))
    }
  }
  
  function utf8Slice (buf, start, end) {
    end = Math.min(buf.length, end)
    var res = []
  
    var i = start
    while (i < end) {
      var firstByte = buf[i]
      var codePoint = null
      var bytesPerSequence = (firstByte > 0xEF) ? 4
        : (firstByte > 0xDF) ? 3
          : (firstByte > 0xBF) ? 2
            : 1
  
      if (i + bytesPerSequence <= end) {
        var secondByte, thirdByte, fourthByte, tempCodePoint
  
        switch (bytesPerSequence) {
          case 1:
            if (firstByte < 0x80) {
              codePoint = firstByte
            }
            break
          case 2:
            secondByte = buf[i + 1]
            if ((secondByte & 0xC0) === 0x80) {
              tempCodePoint = (firstByte & 0x1F) << 0x6 | (secondByte & 0x3F)
              if (tempCodePoint > 0x7F) {
                codePoint = tempCodePoint
              }
            }
            break
          case 3:
            secondByte = buf[i + 1]
            thirdByte = buf[i + 2]
            if ((secondByte & 0xC0) === 0x80 && (thirdByte & 0xC0) === 0x80) {
              tempCodePoint = (firstByte & 0xF) << 0xC | (secondByte & 0x3F) << 0x6 | (thirdByte & 0x3F)
              if (tempCodePoint > 0x7FF && (tempCodePoint < 0xD800 || tempCodePoint > 0xDFFF)) {
                codePoint = tempCodePoint
              }
            }
            break
          case 4:
            secondByte = buf[i + 1]
            thirdByte = buf[i + 2]
            fourthByte = buf[i + 3]
            if ((secondByte & 0xC0) === 0x80 && (thirdByte & 0xC0) === 0x80 && (fourthByte & 0xC0) === 0x80) {
              tempCodePoint = (firstByte & 0xF) << 0x12 | (secondByte & 0x3F) << 0xC | (thirdByte & 0x3F) << 0x6 | (fourthByte & 0x3F)
              if (tempCodePoint > 0xFFFF && tempCodePoint < 0x110000) {
                codePoint = tempCodePoint
              }
            }
        }
      }
  
      if (codePoint === null) {
        // we did not generate a valid codePoint so insert a
        // replacement char (U+FFFD) and advance only 1 byte
        codePoint = 0xFFFD
        bytesPerSequence = 1
      } else if (codePoint > 0xFFFF) {
        // encode to utf16 (surrogate pair dance)
        codePoint -= 0x10000
        res.push(codePoint >>> 10 & 0x3FF | 0xD800)
        codePoint = 0xDC00 | codePoint & 0x3FF
      }
  
      res.push(codePoint)
      i += bytesPerSequence
    }
  
    return decodeCodePointsArray(res)
  }
  
  // Based on http://stackoverflow.com/a/22747272/680742, the browser with
  // the lowest limit is Chrome, with 0x10000 args.
  // We go 1 magnitude less, for safety
  var MAX_ARGUMENTS_LENGTH = 0x1000
  
  function decodeCodePointsArray (codePoints) {
    var len = codePoints.length
    if (len <= MAX_ARGUMENTS_LENGTH) {
      return String.fromCharCode.apply(String, codePoints) // avoid extra slice()
    }
  
    // Decode in chunks to avoid "call stack size exceeded".
    var res = ''
    var i = 0
    while (i < len) {
      res += String.fromCharCode.apply(
        String,
        codePoints.slice(i, i += MAX_ARGUMENTS_LENGTH)
      )
    }
    return res
  }
  
  function asciiSlice (buf, start, end) {
    var ret = ''
    end = Math.min(buf.length, end)
  
    for (var i = start; i < end; ++i) {
      ret += String.fromCharCode(buf[i] & 0x7F)
    }
    return ret
  }
  
  function latin1Slice (buf, start, end) {
    var ret = ''
    end = Math.min(buf.length, end)
  
    for (var i = start; i < end; ++i) {
      ret += String.fromCharCode(buf[i])
    }
    return ret
  }
  
  function hexSlice (buf, start, end) {
    var len = buf.length
  
    if (!start || start < 0) start = 0
    if (!end || end < 0 || end > len) end = len
  
    var out = ''
    for (var i = start; i < end; ++i) {
      out += toHex(buf[i])
    }
    return out
  }
  
  function utf16leSlice (buf, start, end) {
    var bytes = buf.slice(start, end)
    var res = ''
    for (var i = 0; i < bytes.length; i += 2) {
      res += String.fromCharCode(bytes[i] + (bytes[i + 1] * 256))
    }
    return res
  }
  
  Buffer.prototype.slice = function slice (start, end) {
    var len = this.length
    start = ~~start
    end = end === undefined ? len : ~~end
  
    if (start < 0) {
      start += len
      if (start < 0) start = 0
    } else if (start > len) {
      start = len
    }
  
    if (end < 0) {
      end += len
      if (end < 0) end = 0
    } else if (end > len) {
      end = len
    }
  
    if (end < start) end = start
  
    var newBuf = this.subarray(start, end)
    // Return an augmented `Uint8Array` instance
    newBuf.__proto__ = Buffer.prototype
    return newBuf
  }
  
  /*
   * Need to make sure that buffer isn't trying to write out of bounds.
   */
  function checkOffset (offset, ext, length) {
    if ((offset % 1) !== 0 || offset < 0) throw new RangeError('offset is not uint')
    if (offset + ext > length) throw new RangeError('Trying to access beyond buffer length')
  }
  
  Buffer.prototype.readUIntLE = function readUIntLE (offset, byteLength, noAssert) {
    offset = offset >>> 0
    byteLength = byteLength >>> 0
    if (!noAssert) checkOffset(offset, byteLength, this.length)
  
    var val = this[offset]
    var mul = 1
    var i = 0
    while (++i < byteLength && (mul *= 0x100)) {
      val += this[offset + i] * mul
    }
  
    return val
  }
  
  Buffer.prototype.readUIntBE = function readUIntBE (offset, byteLength, noAssert) {
    offset = offset >>> 0
    byteLength = byteLength >>> 0
    if (!noAssert) {
      checkOffset(offset, byteLength, this.length)
    }
  
    var val = this[offset + --byteLength]
    var mul = 1
    while (byteLength > 0 && (mul *= 0x100)) {
      val += this[offset + --byteLength] * mul
    }
  
    return val
  }
  
  Buffer.prototype.readUInt8 = function readUInt8 (offset, noAssert) {
    offset = offset >>> 0
    if (!noAssert) checkOffset(offset, 1, this.length)
    return this[offset]
  }
  
  Buffer.prototype.readUInt16LE = function readUInt16LE (offset, noAssert) {
    offset = offset >>> 0
    if (!noAssert) checkOffset(offset, 2, this.length)
    return this[offset] | (this[offset + 1] << 8)
  }
  
  Buffer.prototype.readUInt16BE = function readUInt16BE (offset, noAssert) {
    offset = offset >>> 0
    if (!noAssert) checkOffset(offset, 2, this.length)
    return (this[offset] << 8) | this[offset + 1]
  }
  
  Buffer.prototype.readUInt32LE = function readUInt32LE (offset, noAssert) {
    offset = offset >>> 0
    if (!noAssert) checkOffset(offset, 4, this.length)
  
    return ((this[offset]) |
        (this[offset + 1] << 8) |
        (this[offset + 2] << 16)) +
        (this[offset + 3] * 0x1000000)
  }
  
  Buffer.prototype.readUInt32BE = function readUInt32BE (offset, noAssert) {
    offset = offset >>> 0
    if (!noAssert) checkOffset(offset, 4, this.length)
  
    return (this[offset] * 0x1000000) +
      ((this[offset + 1] << 16) |
      (this[offset + 2] << 8) |
      this[offset + 3])
  }
  
  Buffer.prototype.readIntLE = function readIntLE (offset, byteLength, noAssert) {
    offset = offset >>> 0
    byteLength = byteLength >>> 0
    if (!noAssert) checkOffset(offset, byteLength, this.length)
  
    var val = this[offset]
    var mul = 1
    var i = 0
    while (++i < byteLength && (mul *= 0x100)) {
      val += this[offset + i] * mul
    }
    mul *= 0x80
  
    if (val >= mul) val -= Math.pow(2, 8 * byteLength)
  
    return val
  }
  
  Buffer.prototype.readIntBE = function readIntBE (offset, byteLength, noAssert) {
    offset = offset >>> 0
    byteLength = byteLength >>> 0
    if (!noAssert) checkOffset(offset, byteLength, this.length)
  
    var i = byteLength
    var mul = 1
    var val = this[offset + --i]
    while (i > 0 && (mul *= 0x100)) {
      val += this[offset + --i] * mul
    }
    mul *= 0x80
  
    if (val >= mul) val -= Math.pow(2, 8 * byteLength)
  
    return val
  }
  
  Buffer.prototype.readInt8 = function readInt8 (offset, noAssert) {
    offset = offset >>> 0
    if (!noAssert) checkOffset(offset, 1, this.length)
    if (!(this[offset] & 0x80)) return (this[offset])
    return ((0xff - this[offset] + 1) * -1)
  }
  
  Buffer.prototype.readInt16LE = function readInt16LE (offset, noAssert) {
    offset = offset >>> 0
    if (!noAssert) checkOffset(offset, 2, this.length)
    var val = this[offset] | (this[offset + 1] << 8)
    return (val & 0x8000) ? val | 0xFFFF0000 : val
  }
  
  Buffer.prototype.readInt16BE = function readInt16BE (offset, noAssert) {
    offset = offset >>> 0
    if (!noAssert) checkOffset(offset, 2, this.length)
    var val = this[offset + 1] | (this[offset] << 8)
    return (val & 0x8000) ? val | 0xFFFF0000 : val
  }
  
  Buffer.prototype.readInt32LE = function readInt32LE (offset, noAssert) {
    offset = offset >>> 0
    if (!noAssert) checkOffset(offset, 4, this.length)
  
    return (this[offset]) |
      (this[offset + 1] << 8) |
      (this[offset + 2] << 16) |
      (this[offset + 3] << 24)
  }
  
  Buffer.prototype.readInt32BE = function readInt32BE (offset, noAssert) {
    offset = offset >>> 0
    if (!noAssert) checkOffset(offset, 4, this.length)
  
    return (this[offset] << 24) |
      (this[offset + 1] << 16) |
      (this[offset + 2] << 8) |
      (this[offset + 3])
  }
  
  Buffer.prototype.readFloatLE = function readFloatLE (offset, noAssert) {
    offset = offset >>> 0
    if (!noAssert) checkOffset(offset, 4, this.length)
    return ieee754.read(this, offset, true, 23, 4)
  }
  
  Buffer.prototype.readFloatBE = function readFloatBE (offset, noAssert) {
    offset = offset >>> 0
    if (!noAssert) checkOffset(offset, 4, this.length)
    return ieee754.read(this, offset, false, 23, 4)
  }
  
  Buffer.prototype.readDoubleLE = function readDoubleLE (offset, noAssert) {
    offset = offset >>> 0
    if (!noAssert) checkOffset(offset, 8, this.length)
    return ieee754.read(this, offset, true, 52, 8)
  }
  
  Buffer.prototype.readDoubleBE = function readDoubleBE (offset, noAssert) {
    offset = offset >>> 0
    if (!noAssert) checkOffset(offset, 8, this.length)
    return ieee754.read(this, offset, false, 52, 8)
  }
  
  function checkInt (buf, value, offset, ext, max, min) {
    if (!Buffer.isBuffer(buf)) throw new TypeError('"buffer" argument must be a Buffer instance')
    if (value > max || value < min) throw new RangeError('"value" argument is out of bounds')
    if (offset + ext > buf.length) throw new RangeError('Index out of range')
  }
  
  Buffer.prototype.writeUIntLE = function writeUIntLE (value, offset, byteLength, noAssert) {
    value = +value
    offset = offset >>> 0
    byteLength = byteLength >>> 0
    if (!noAssert) {
      var maxBytes = Math.pow(2, 8 * byteLength) - 1
      checkInt(this, value, offset, byteLength, maxBytes, 0)
    }
  
    var mul = 1
    var i = 0
    this[offset] = value & 0xFF
    while (++i < byteLength && (mul *= 0x100)) {
      this[offset + i] = (value / mul) & 0xFF
    }
  
    return offset + byteLength
  }
  
  Buffer.prototype.writeUIntBE = function writeUIntBE (value, offset, byteLength, noAssert) {
    value = +value
    offset = offset >>> 0
    byteLength = byteLength >>> 0
    if (!noAssert) {
      var maxBytes = Math.pow(2, 8 * byteLength) - 1
      checkInt(this, value, offset, byteLength, maxBytes, 0)
    }
  
    var i = byteLength - 1
    var mul = 1
    this[offset + i] = value & 0xFF
    while (--i >= 0 && (mul *= 0x100)) {
      this[offset + i] = (value / mul) & 0xFF
    }
  
    return offset + byteLength
  }
  
  Buffer.prototype.writeUInt8 = function writeUInt8 (value, offset, noAssert) {
    value = +value
    offset = offset >>> 0
    if (!noAssert) checkInt(this, value, offset, 1, 0xff, 0)
    this[offset] = (value & 0xff)
    return offset + 1
  }
  
  Buffer.prototype.writeUInt16LE = function writeUInt16LE (value, offset, noAssert) {
    value = +value
    offset = offset >>> 0
    if (!noAssert) checkInt(this, value, offset, 2, 0xffff, 0)
    this[offset] = (value & 0xff)
    this[offset + 1] = (value >>> 8)
    return offset + 2
  }
  
  Buffer.prototype.writeUInt16BE = function writeUInt16BE (value, offset, noAssert) {
    value = +value
    offset = offset >>> 0
    if (!noAssert) checkInt(this, value, offset, 2, 0xffff, 0)
    this[offset] = (value >>> 8)
    this[offset + 1] = (value & 0xff)
    return offset + 2
  }
  
  Buffer.prototype.writeUInt32LE = function writeUInt32LE (value, offset, noAssert) {
    value = +value
    offset = offset >>> 0
    if (!noAssert) checkInt(this, value, offset, 4, 0xffffffff, 0)
    this[offset + 3] = (value >>> 24)
    this[offset + 2] = (value >>> 16)
    this[offset + 1] = (value >>> 8)
    this[offset] = (value & 0xff)
    return offset + 4
  }
  
  Buffer.prototype.writeUInt32BE = function writeUInt32BE (value, offset, noAssert) {
    value = +value
    offset = offset >>> 0
    if (!noAssert) checkInt(this, value, offset, 4, 0xffffffff, 0)
    this[offset] = (value >>> 24)
    this[offset + 1] = (value >>> 16)
    this[offset + 2] = (value >>> 8)
    this[offset + 3] = (value & 0xff)
    return offset + 4
  }
  
  Buffer.prototype.writeIntLE = function writeIntLE (value, offset, byteLength, noAssert) {
    value = +value
    offset = offset >>> 0
    if (!noAssert) {
      var limit = Math.pow(2, (8 * byteLength) - 1)
  
      checkInt(this, value, offset, byteLength, limit - 1, -limit)
    }
  
    var i = 0
    var mul = 1
    var sub = 0
    this[offset] = value & 0xFF
    while (++i < byteLength && (mul *= 0x100)) {
      if (value < 0 && sub === 0 && this[offset + i - 1] !== 0) {
        sub = 1
      }
      this[offset + i] = ((value / mul) >> 0) - sub & 0xFF
    }
  
    return offset + byteLength
  }
  
  Buffer.prototype.writeIntBE = function writeIntBE (value, offset, byteLength, noAssert) {
    value = +value
    offset = offset >>> 0
    if (!noAssert) {
      var limit = Math.pow(2, (8 * byteLength) - 1)
  
      checkInt(this, value, offset, byteLength, limit - 1, -limit)
    }
  
    var i = byteLength - 1
    var mul = 1
    var sub = 0
    this[offset + i] = value & 0xFF
    while (--i >= 0 && (mul *= 0x100)) {
      if (value < 0 && sub === 0 && this[offset + i + 1] !== 0) {
        sub = 1
      }
      this[offset + i] = ((value / mul) >> 0) - sub & 0xFF
    }
  
    return offset + byteLength
  }
  
  Buffer.prototype.writeInt8 = function writeInt8 (value, offset, noAssert) {
    value = +value
    offset = offset >>> 0
    if (!noAssert) checkInt(this, value, offset, 1, 0x7f, -0x80)
    if (value < 0) value = 0xff + value + 1
    this[offset] = (value & 0xff)
    return offset + 1
  }
  
  Buffer.prototype.writeInt16LE = function writeInt16LE (value, offset, noAssert) {
    value = +value
    offset = offset >>> 0
    if (!noAssert) checkInt(this, value, offset, 2, 0x7fff, -0x8000)
    this[offset] = (value & 0xff)
    this[offset + 1] = (value >>> 8)
    return offset + 2
  }
  
  Buffer.prototype.writeInt16BE = function writeInt16BE (value, offset, noAssert) {
    value = +value
    offset = offset >>> 0
    if (!noAssert) checkInt(this, value, offset, 2, 0x7fff, -0x8000)
    this[offset] = (value >>> 8)
    this[offset + 1] = (value & 0xff)
    return offset + 2
  }
  
  Buffer.prototype.writeInt32LE = function writeInt32LE (value, offset, noAssert) {
    value = +value
    offset = offset >>> 0
    if (!noAssert) checkInt(this, value, offset, 4, 0x7fffffff, -0x80000000)
    this[offset] = (value & 0xff)
    this[offset + 1] = (value >>> 8)
    this[offset + 2] = (value >>> 16)
    this[offset + 3] = (value >>> 24)
    return offset + 4
  }
  
  Buffer.prototype.writeInt32BE = function writeInt32BE (value, offset, noAssert) {
    value = +value
    offset = offset >>> 0
    if (!noAssert) checkInt(this, value, offset, 4, 0x7fffffff, -0x80000000)
    if (value < 0) value = 0xffffffff + value + 1
    this[offset] = (value >>> 24)
    this[offset + 1] = (value >>> 16)
    this[offset + 2] = (value >>> 8)
    this[offset + 3] = (value & 0xff)
    return offset + 4
  }
  
  function checkIEEE754 (buf, value, offset, ext, max, min) {
    if (offset + ext > buf.length) throw new RangeError('Index out of range')
    if (offset < 0) throw new RangeError('Index out of range')
  }
  
  function writeFloat (buf, value, offset, littleEndian, noAssert) {
    value = +value
    offset = offset >>> 0
    if (!noAssert) {
      checkIEEE754(buf, value, offset, 4, 3.4028234663852886e+38, -3.4028234663852886e+38)
    }
    ieee754.write(buf, value, offset, littleEndian, 23, 4)
    return offset + 4
  }
  
  Buffer.prototype.writeFloatLE = function writeFloatLE (value, offset, noAssert) {
    return writeFloat(this, value, offset, true, noAssert)
  }
  
  Buffer.prototype.writeFloatBE = function writeFloatBE (value, offset, noAssert) {
    return writeFloat(this, value, offset, false, noAssert)
  }
  
  function writeDouble (buf, value, offset, littleEndian, noAssert) {
    value = +value
    offset = offset >>> 0
    if (!noAssert) {
      checkIEEE754(buf, value, offset, 8, 1.7976931348623157E+308, -1.7976931348623157E+308)
    }
    ieee754.write(buf, value, offset, littleEndian, 52, 8)
    return offset + 8
  }
  
  Buffer.prototype.writeDoubleLE = function writeDoubleLE (value, offset, noAssert) {
    return writeDouble(this, value, offset, true, noAssert)
  }
  
  Buffer.prototype.writeDoubleBE = function writeDoubleBE (value, offset, noAssert) {
    return writeDouble(this, value, offset, false, noAssert)
  }
  
  // copy(targetBuffer, targetStart=0, sourceStart=0, sourceEnd=buffer.length)
  Buffer.prototype.copy = function copy (target, targetStart, start, end) {
    if (!Buffer.isBuffer(target)) throw new TypeError('argument should be a Buffer')
    if (!start) start = 0
    if (!end && end !== 0) end = this.length
    if (targetStart >= target.length) targetStart = target.length
    if (!targetStart) targetStart = 0
    if (end > 0 && end < start) end = start
  
    // Copy 0 bytes; we're done
    if (end === start) return 0
    if (target.length === 0 || this.length === 0) return 0
  
    // Fatal error conditions
    if (targetStart < 0) {
      throw new RangeError('targetStart out of bounds')
    }
    if (start < 0 || start >= this.length) throw new RangeError('Index out of range')
    if (end < 0) throw new RangeError('sourceEnd out of bounds')
  
    // Are we oob?
    if (end > this.length) end = this.length
    if (target.length - targetStart < end - start) {
      end = target.length - targetStart + start
    }
  
    var len = end - start
  
    if (this === target && typeof Uint8Array.prototype.copyWithin === 'function') {
      // Use built-in when available, missing from IE11
      this.copyWithin(targetStart, start, end)
    } else if (this === target && start < targetStart && targetStart < end) {
      // descending copy from end
      for (var i = len - 1; i >= 0; --i) {
        target[i + targetStart] = this[i + start]
      }
    } else {
      Uint8Array.prototype.set.call(
        target,
        this.subarray(start, end),
        targetStart
      )
    }
  
    return len
  }
  
  // Usage:
  //    buffer.fill(number[, offset[, end]])
  //    buffer.fill(buffer[, offset[, end]])
  //    buffer.fill(string[, offset[, end]][, encoding])
  Buffer.prototype.fill = function fill (val, start, end, encoding) {
    // Handle string cases:
    if (typeof val === 'string') {
      if (typeof start === 'string') {
        encoding = start
        start = 0
        end = this.length
      } else if (typeof end === 'string') {
        encoding = end
        end = this.length
      }
      if (encoding !== undefined && typeof encoding !== 'string') {
        throw new TypeError('encoding must be a string')
      }
      if (typeof encoding === 'string' && !Buffer.isEncoding(encoding)) {
        throw new TypeError('Unknown encoding: ' + encoding)
      }
      if (val.length === 1) {
        var code = val.charCodeAt(0)
        if ((encoding === 'utf8' && code < 128) ||
            encoding === 'latin1') {
          // Fast path: If `val` fits into a single byte, use that numeric value.
          val = code
        }
      }
    } else if (typeof val === 'number') {
      val = val & 255
    }
  
    // Invalid ranges are not set to a default, so can range check early.
    if (start < 0 || this.length < start || this.length < end) {
      throw new RangeError('Out of range index')
    }
  
    if (end <= start) {
      return this
    }
  
    start = start >>> 0
    end = end === undefined ? this.length : end >>> 0
  
    if (!val) val = 0
  
    var i
    if (typeof val === 'number') {
      for (i = start; i < end; ++i) {
        this[i] = val
      }
    } else {
      var bytes = Buffer.isBuffer(val)
        ? val
        : Buffer.from(val, encoding)
      var len = bytes.length
      if (len === 0) {
        throw new TypeError('The value "' + val +
          '" is invalid for argument "value"')
      }
      for (i = 0; i < end - start; ++i) {
        this[i + start] = bytes[i % len]
      }
    }
  
    return this
  }
  
  // HELPER FUNCTIONS
  // ================
  
  var INVALID_BASE64_RE = /[^+/0-9A-Za-z-_]/g
  
  function base64clean (str) {
    // Node takes equal signs as end of the Base64 encoding
    str = str.split('=')[0]
    // Node strips out invalid characters like \n and \t from the string, base64-js does not
    str = str.trim().replace(INVALID_BASE64_RE, '')
    // Node converts strings with length < 2 to ''
    if (str.length < 2) return ''
    // Node allows for non-padded base64 strings (missing trailing ===), base64-js does not
    while (str.length % 4 !== 0) {
      str = str + '='
    }
    return str
  }
  
  function toHex (n) {
    if (n < 16) return '0' + n.toString(16)
    return n.toString(16)
  }
  
  function utf8ToBytes (string, units) {
    units = units || Infinity
    var codePoint
    var length = string.length
    var leadSurrogate = null
    var bytes = []
  
    for (var i = 0; i < length; ++i) {
      codePoint = string.charCodeAt(i)
  
      // is surrogate component
      if (codePoint > 0xD7FF && codePoint < 0xE000) {
        // last char was a lead
        if (!leadSurrogate) {
          // no lead yet
          if (codePoint > 0xDBFF) {
            // unexpected trail
            if ((units -= 3) > -1) bytes.push(0xEF, 0xBF, 0xBD)
            continue
          } else if (i + 1 === length) {
            // unpaired lead
            if ((units -= 3) > -1) bytes.push(0xEF, 0xBF, 0xBD)
            continue
          }
  
          // valid lead
          leadSurrogate = codePoint
  
          continue
        }
  
        // 2 leads in a row
        if (codePoint < 0xDC00) {
          if ((units -= 3) > -1) bytes.push(0xEF, 0xBF, 0xBD)
          leadSurrogate = codePoint
          continue
        }
  
        // valid surrogate pair
        codePoint = (leadSurrogate - 0xD800 << 10 | codePoint - 0xDC00) + 0x10000
      } else if (leadSurrogate) {
        // valid bmp char, but last char was a lead
        if ((units -= 3) > -1) bytes.push(0xEF, 0xBF, 0xBD)
      }
  
      leadSurrogate = null
  
      // encode utf8
      if (codePoint < 0x80) {
        if ((units -= 1) < 0) break
        bytes.push(codePoint)
      } else if (codePoint < 0x800) {
        if ((units -= 2) < 0) break
        bytes.push(
          codePoint >> 0x6 | 0xC0,
          codePoint & 0x3F | 0x80
        )
      } else if (codePoint < 0x10000) {
        if ((units -= 3) < 0) break
        bytes.push(
          codePoint >> 0xC | 0xE0,
          codePoint >> 0x6 & 0x3F | 0x80,
          codePoint & 0x3F | 0x80
        )
      } else if (codePoint < 0x110000) {
        if ((units -= 4) < 0) break
        bytes.push(
          codePoint >> 0x12 | 0xF0,
          codePoint >> 0xC & 0x3F | 0x80,
          codePoint >> 0x6 & 0x3F | 0x80,
          codePoint & 0x3F | 0x80
        )
      } else {
        throw new Error('Invalid code point')
      }
    }
  
    return bytes
  }
  
  function asciiToBytes (str) {
    var byteArray = []
    for (var i = 0; i < str.length; ++i) {
      // Node's code seems to be doing this and not & 0x7F..
      byteArray.push(str.charCodeAt(i) & 0xFF)
    }
    return byteArray
  }
  
  function utf16leToBytes (str, units) {
    var c, hi, lo
    var byteArray = []
    for (var i = 0; i < str.length; ++i) {
      if ((units -= 2) < 0) break
  
      c = str.charCodeAt(i)
      hi = c >> 8
      lo = c % 256
      byteArray.push(lo)
      byteArray.push(hi)
    }
  
    return byteArray
  }
  
  function base64ToBytes (str) {
    return base64.toByteArray(base64clean(str))
  }
  
  function blitBuffer (src, dst, offset, length) {
    for (var i = 0; i < length; ++i) {
      if ((i + offset >= dst.length) || (i >= src.length)) break
      dst[i + offset] = src[i]
    }
    return i
  }
  
  // ArrayBuffer or Uint8Array objects from other contexts (i.e. iframes) do not pass
  // the `instanceof` check but they should be treated as of that type.
  // See: https://github.com/feross/buffer/issues/166
  function isInstance (obj, type) {
    return obj instanceof type ||
      (obj != null && obj.constructor != null && obj.constructor.name != null &&
        obj.constructor.name === type.name)
  }
  function numberIsNaN (obj) {
    // For IE11 support
    return obj !== obj // eslint-disable-line no-self-compare
  }
  
  }).call(this,require("buffer").Buffer)
  },{"base64-js":10,"buffer":12,"ieee754":28}],13:[function(require,module,exports){
  (function (Buffer){
  // Copyright Joyent, Inc. and other Node contributors.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a
  // copy of this software and associated documentation files (the
  // "Software"), to deal in the Software without restriction, including
  // without limitation the rights to use, copy, modify, merge, publish,
  // distribute, sublicense, and/or sell copies of the Software, and to permit
  // persons to whom the Software is furnished to do so, subject to the
  // following conditions:
  //
  // The above copyright notice and this permission notice shall be included
  // in all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
  // NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
  // DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  // USE OR OTHER DEALINGS IN THE SOFTWARE.
  
  // NOTE: These type checking functions intentionally don't use `instanceof`
  // because it is fragile and can be easily faked with `Object.create()`.
  
  function isArray(arg) {
    if (Array.isArray) {
      return Array.isArray(arg);
    }
    return objectToString(arg) === '[object Array]';
  }
  exports.isArray = isArray;
  
  function isBoolean(arg) {
    return typeof arg === 'boolean';
  }
  exports.isBoolean = isBoolean;
  
  function isNull(arg) {
    return arg === null;
  }
  exports.isNull = isNull;
  
  function isNullOrUndefined(arg) {
    return arg == null;
  }
  exports.isNullOrUndefined = isNullOrUndefined;
  
  function isNumber(arg) {
    return typeof arg === 'number';
  }
  exports.isNumber = isNumber;
  
  function isString(arg) {
    return typeof arg === 'string';
  }
  exports.isString = isString;
  
  function isSymbol(arg) {
    return typeof arg === 'symbol';
  }
  exports.isSymbol = isSymbol;
  
  function isUndefined(arg) {
    return arg === void 0;
  }
  exports.isUndefined = isUndefined;
  
  function isRegExp(re) {
    return objectToString(re) === '[object RegExp]';
  }
  exports.isRegExp = isRegExp;
  
  function isObject(arg) {
    return typeof arg === 'object' && arg !== null;
  }
  exports.isObject = isObject;
  
  function isDate(d) {
    return objectToString(d) === '[object Date]';
  }
  exports.isDate = isDate;
  
  function isError(e) {
    return (objectToString(e) === '[object Error]' || e instanceof Error);
  }
  exports.isError = isError;
  
  function isFunction(arg) {
    return typeof arg === 'function';
  }
  exports.isFunction = isFunction;
  
  function isPrimitive(arg) {
    return arg === null ||
           typeof arg === 'boolean' ||
           typeof arg === 'number' ||
           typeof arg === 'string' ||
           typeof arg === 'symbol' ||  // ES6 symbol
           typeof arg === 'undefined';
  }
  exports.isPrimitive = isPrimitive;
  
  exports.isBuffer = Buffer.isBuffer;
  
  function objectToString(o) {
    return Object.prototype.toString.call(o);
  }
  
  }).call(this,{"isBuffer":require("../../is-buffer/index.js")})
  },{"../../is-buffer/index.js":30}],14:[function(require,module,exports){
  (function (process){
  /* eslint-env browser */
  
  /**
   * This is the web browser implementation of `debug()`.
   */
  
  exports.log = log;
  exports.formatArgs = formatArgs;
  exports.save = save;
  exports.load = load;
  exports.useColors = useColors;
  exports.storage = localstorage();
  
  /**
   * Colors.
   */
  
  exports.colors = [
  	'#0000CC',
  	'#0000FF',
  	'#0033CC',
  	'#0033FF',
  	'#0066CC',
  	'#0066FF',
  	'#0099CC',
  	'#0099FF',
  	'#00CC00',
  	'#00CC33',
  	'#00CC66',
  	'#00CC99',
  	'#00CCCC',
  	'#00CCFF',
  	'#3300CC',
  	'#3300FF',
  	'#3333CC',
  	'#3333FF',
  	'#3366CC',
  	'#3366FF',
  	'#3399CC',
  	'#3399FF',
  	'#33CC00',
  	'#33CC33',
  	'#33CC66',
  	'#33CC99',
  	'#33CCCC',
  	'#33CCFF',
  	'#6600CC',
  	'#6600FF',
  	'#6633CC',
  	'#6633FF',
  	'#66CC00',
  	'#66CC33',
  	'#9900CC',
  	'#9900FF',
  	'#9933CC',
  	'#9933FF',
  	'#99CC00',
  	'#99CC33',
  	'#CC0000',
  	'#CC0033',
  	'#CC0066',
  	'#CC0099',
  	'#CC00CC',
  	'#CC00FF',
  	'#CC3300',
  	'#CC3333',
  	'#CC3366',
  	'#CC3399',
  	'#CC33CC',
  	'#CC33FF',
  	'#CC6600',
  	'#CC6633',
  	'#CC9900',
  	'#CC9933',
  	'#CCCC00',
  	'#CCCC33',
  	'#FF0000',
  	'#FF0033',
  	'#FF0066',
  	'#FF0099',
  	'#FF00CC',
  	'#FF00FF',
  	'#FF3300',
  	'#FF3333',
  	'#FF3366',
  	'#FF3399',
  	'#FF33CC',
  	'#FF33FF',
  	'#FF6600',
  	'#FF6633',
  	'#FF9900',
  	'#FF9933',
  	'#FFCC00',
  	'#FFCC33'
  ];
  
  /**
   * Currently only WebKit-based Web Inspectors, Firefox >= v31,
   * and the Firebug extension (any Firefox version) are known
   * to support "%c" CSS customizations.
   *
   * TODO: add a `localStorage` variable to explicitly enable/disable colors
   */
  
  // eslint-disable-next-line complexity
  function useColors() {
  	// NB: In an Electron preload script, document will be defined but not fully
  	// initialized. Since we know we're in Chrome, we'll just detect this case
  	// explicitly
  	if (typeof window !== 'undefined' && window.process && (window.process.type === 'renderer' || window.process.__nwjs)) {
  		return true;
  	}
  
  	// Internet Explorer and Edge do not support colors.
  	if (typeof navigator !== 'undefined' && navigator.userAgent && navigator.userAgent.toLowerCase().match(/(edge|trident)\/(\d+)/)) {
  		return false;
  	}
  
  	// Is webkit? http://stackoverflow.com/a/16459606/376773
  	// document is undefined in react-native: https://github.com/facebook/react-native/pull/1632
  	return (typeof document !== 'undefined' && document.documentElement && document.documentElement.style && document.documentElement.style.WebkitAppearance) ||
  		// Is firebug? http://stackoverflow.com/a/398120/376773
  		(typeof window !== 'undefined' && window.console && (window.console.firebug || (window.console.exception && window.console.table))) ||
  		// Is firefox >= v31?
  		// https://developer.mozilla.org/en-US/docs/Tools/Web_Console#Styling_messages
  		(typeof navigator !== 'undefined' && navigator.userAgent && navigator.userAgent.toLowerCase().match(/firefox\/(\d+)/) && parseInt(RegExp.$1, 10) >= 31) ||
  		// Double check webkit in userAgent just in case we are in a worker
  		(typeof navigator !== 'undefined' && navigator.userAgent && navigator.userAgent.toLowerCase().match(/applewebkit\/(\d+)/));
  }
  
  /**
   * Colorize log arguments if enabled.
   *
   * @api public
   */
  
  function formatArgs(args) {
  	args[0] = (this.useColors ? '%c' : '') +
  		this.namespace +
  		(this.useColors ? ' %c' : ' ') +
  		args[0] +
  		(this.useColors ? '%c ' : ' ') +
  		'+' + module.exports.humanize(this.diff);
  
  	if (!this.useColors) {
  		return;
  	}
  
  	const c = 'color: ' + this.color;
  	args.splice(1, 0, c, 'color: inherit');
  
  	// The final "%c" is somewhat tricky, because there could be other
  	// arguments passed either before or after the %c, so we need to
  	// figure out the correct index to insert the CSS into
  	let index = 0;
  	let lastC = 0;
  	args[0].replace(/%[a-zA-Z%]/g, match => {
  		if (match === '%%') {
  			return;
  		}
  		index++;
  		if (match === '%c') {
  			// We only are interested in the *last* %c
  			// (the user may have provided their own)
  			lastC = index;
  		}
  	});
  
  	args.splice(lastC, 0, c);
  }
  
  /**
   * Invokes `console.log()` when available.
   * No-op when `console.log` is not a "function".
   *
   * @api public
   */
  function log(...args) {
  	// This hackery is required for IE8/9, where
  	// the `console.log` function doesn't have 'apply'
  	return typeof console === 'object' &&
  		console.log &&
  		console.log(...args);
  }
  
  /**
   * Save `namespaces`.
   *
   * @param {String} namespaces
   * @api private
   */
  function save(namespaces) {
  	try {
  		if (namespaces) {
  			exports.storage.setItem('debug', namespaces);
  		} else {
  			exports.storage.removeItem('debug');
  		}
  	} catch (error) {
  		// Swallow
  		// XXX (@Qix-) should we be logging these?
  	}
  }
  
  /**
   * Load `namespaces`.
   *
   * @return {String} returns the previously persisted debug modes
   * @api private
   */
  function load() {
  	let r;
  	try {
  		r = exports.storage.getItem('debug');
  	} catch (error) {
  		// Swallow
  		// XXX (@Qix-) should we be logging these?
  	}
  
  	// If debug isn't set in LS, and we're in Electron, try to load $DEBUG
  	if (!r && typeof process !== 'undefined' && 'env' in process) {
  		r = process.env.DEBUG;
  	}
  
  	return r;
  }
  
  /**
   * Localstorage attempts to return the localstorage.
   *
   * This is necessary because safari throws
   * when a user disables cookies/localstorage
   * and you attempt to access it.
   *
   * @return {LocalStorage}
   * @api private
   */
  
  function localstorage() {
  	try {
  		// TVMLKit (Apple TV JS Runtime) does not have a window object, just localStorage in the global context
  		// The Browser also has localStorage in the global context.
  		return localStorage;
  	} catch (error) {
  		// Swallow
  		// XXX (@Qix-) should we be logging these?
  	}
  }
  
  module.exports = require('./common')(exports);
  
  const {formatters} = module.exports;
  
  /**
   * Map %j to `JSON.stringify()`, since no Web Inspectors do that by default.
   */
  
  formatters.j = function (v) {
  	try {
  		return JSON.stringify(v);
  	} catch (error) {
  		return '[UnexpectedJSONParseError]: ' + error.message;
  	}
  };
  
  }).call(this,require('_process'))
  },{"./common":15,"_process":44}],15:[function(require,module,exports){
  
  /**
   * This is the common logic for both the Node.js and web browser
   * implementations of `debug()`.
   */
  
  function setup(env) {
  	createDebug.debug = createDebug;
  	createDebug.default = createDebug;
  	createDebug.coerce = coerce;
  	createDebug.disable = disable;
  	createDebug.enable = enable;
  	createDebug.enabled = enabled;
  	createDebug.humanize = require('ms');
  
  	Object.keys(env).forEach(key => {
  		createDebug[key] = env[key];
  	});
  
  	/**
  	* Active `debug` instances.
  	*/
  	createDebug.instances = [];
  
  	/**
  	* The currently active debug mode names, and names to skip.
  	*/
  
  	createDebug.names = [];
  	createDebug.skips = [];
  
  	/**
  	* Map of special "%n" handling functions, for the debug "format" argument.
  	*
  	* Valid key names are a single, lower or upper-case letter, i.e. "n" and "N".
  	*/
  	createDebug.formatters = {};
  
  	/**
  	* Selects a color for a debug namespace
  	* @param {String} namespace The namespace string for the for the debug instance to be colored
  	* @return {Number|String} An ANSI color code for the given namespace
  	* @api private
  	*/
  	function selectColor(namespace) {
  		let hash = 0;
  
  		for (let i = 0; i < namespace.length; i++) {
  			hash = ((hash << 5) - hash) + namespace.charCodeAt(i);
  			hash |= 0; // Convert to 32bit integer
  		}
  
  		return createDebug.colors[Math.abs(hash) % createDebug.colors.length];
  	}
  	createDebug.selectColor = selectColor;
  
  	/**
  	* Create a debugger with the given `namespace`.
  	*
  	* @param {String} namespace
  	* @return {Function}
  	* @api public
  	*/
  	function createDebug(namespace) {
  		let prevTime;
  
  		function debug(...args) {
  			// Disabled?
  			if (!debug.enabled) {
  				return;
  			}
  
  			const self = debug;
  
  			// Set `diff` timestamp
  			const curr = Number(new Date());
  			const ms = curr - (prevTime || curr);
  			self.diff = ms;
  			self.prev = prevTime;
  			self.curr = curr;
  			prevTime = curr;
  
  			args[0] = createDebug.coerce(args[0]);
  
  			if (typeof args[0] !== 'string') {
  				// Anything else let's inspect with %O
  				args.unshift('%O');
  			}
  
  			// Apply any `formatters` transformations
  			let index = 0;
  			args[0] = args[0].replace(/%([a-zA-Z%])/g, (match, format) => {
  				// If we encounter an escaped % then don't increase the array index
  				if (match === '%%') {
  					return match;
  				}
  				index++;
  				const formatter = createDebug.formatters[format];
  				if (typeof formatter === 'function') {
  					const val = args[index];
  					match = formatter.call(self, val);
  
  					// Now we need to remove `args[index]` since it's inlined in the `format`
  					args.splice(index, 1);
  					index--;
  				}
  				return match;
  			});
  
  			// Apply env-specific formatting (colors, etc.)
  			createDebug.formatArgs.call(self, args);
  
  			const logFn = self.log || createDebug.log;
  			logFn.apply(self, args);
  		}
  
  		debug.namespace = namespace;
  		debug.enabled = createDebug.enabled(namespace);
  		debug.useColors = createDebug.useColors();
  		debug.color = selectColor(namespace);
  		debug.destroy = destroy;
  		debug.extend = extend;
  		// Debug.formatArgs = formatArgs;
  		// debug.rawLog = rawLog;
  
  		// env-specific initialization logic for debug instances
  		if (typeof createDebug.init === 'function') {
  			createDebug.init(debug);
  		}
  
  		createDebug.instances.push(debug);
  
  		return debug;
  	}
  
  	function destroy() {
  		const index = createDebug.instances.indexOf(this);
  		if (index !== -1) {
  			createDebug.instances.splice(index, 1);
  			return true;
  		}
  		return false;
  	}
  
  	function extend(namespace, delimiter) {
  		const newDebug = createDebug(this.namespace + (typeof delimiter === 'undefined' ? ':' : delimiter) + namespace);
  		newDebug.log = this.log;
  		return newDebug;
  	}
  
  	/**
  	* Enables a debug mode by namespaces. This can include modes
  	* separated by a colon and wildcards.
  	*
  	* @param {String} namespaces
  	* @api public
  	*/
  	function enable(namespaces) {
  		createDebug.save(namespaces);
  
  		createDebug.names = [];
  		createDebug.skips = [];
  
  		let i;
  		const split = (typeof namespaces === 'string' ? namespaces : '').split(/[\s,]+/);
  		const len = split.length;
  
  		for (i = 0; i < len; i++) {
  			if (!split[i]) {
  				// ignore empty strings
  				continue;
  			}
  
  			namespaces = split[i].replace(/\*/g, '.*?');
  
  			if (namespaces[0] === '-') {
  				createDebug.skips.push(new RegExp('^' + namespaces.substr(1) + '$'));
  			} else {
  				createDebug.names.push(new RegExp('^' + namespaces + '$'));
  			}
  		}
  
  		for (i = 0; i < createDebug.instances.length; i++) {
  			const instance = createDebug.instances[i];
  			instance.enabled = createDebug.enabled(instance.namespace);
  		}
  	}
  
  	/**
  	* Disable debug output.
  	*
  	* @return {String} namespaces
  	* @api public
  	*/
  	function disable() {
  		const namespaces = [
  			...createDebug.names.map(toNamespace),
  			...createDebug.skips.map(toNamespace).map(namespace => '-' + namespace)
  		].join(',');
  		createDebug.enable('');
  		return namespaces;
  	}
  
  	/**
  	* Returns true if the given mode name is enabled, false otherwise.
  	*
  	* @param {String} name
  	* @return {Boolean}
  	* @api public
  	*/
  	function enabled(name) {
  		if (name[name.length - 1] === '*') {
  			return true;
  		}
  
  		let i;
  		let len;
  
  		for (i = 0, len = createDebug.skips.length; i < len; i++) {
  			if (createDebug.skips[i].test(name)) {
  				return false;
  			}
  		}
  
  		for (i = 0, len = createDebug.names.length; i < len; i++) {
  			if (createDebug.names[i].test(name)) {
  				return true;
  			}
  		}
  
  		return false;
  	}
  
  	/**
  	* Convert regexp to namespace
  	*
  	* @param {RegExp} regxep
  	* @return {String} namespace
  	* @api private
  	*/
  	function toNamespace(regexp) {
  		return regexp.toString()
  			.substring(2, regexp.toString().length - 2)
  			.replace(/\.\*\?$/, '*');
  	}
  
  	/**
  	* Coerce `val`.
  	*
  	* @param {Mixed} val
  	* @return {Mixed}
  	* @api private
  	*/
  	function coerce(val) {
  		if (val instanceof Error) {
  			return val.stack || val.message;
  		}
  		return val;
  	}
  
  	createDebug.enable(createDebug.load());
  
  	return createDebug;
  }
  
  module.exports = setup;
  
  },{"ms":41}],16:[function(require,module,exports){
  (function (process,Buffer){
  var stream = require('readable-stream')
  var eos = require('end-of-stream')
  var inherits = require('inherits')
  var shift = require('stream-shift')
  
  var SIGNAL_FLUSH = (Buffer.from && Buffer.from !== Uint8Array.from)
    ? Buffer.from([0])
    : new Buffer([0])
  
  var onuncork = function(self, fn) {
    if (self._corked) self.once('uncork', fn)
    else fn()
  }
  
  var autoDestroy = function (self, err) {
    if (self._autoDestroy) self.destroy(err)
  }
  
  var destroyer = function(self, end) {
    return function(err) {
      if (err) autoDestroy(self, err.message === 'premature close' ? null : err)
      else if (end && !self._ended) self.end()
    }
  }
  
  var end = function(ws, fn) {
    if (!ws) return fn()
    if (ws._writableState && ws._writableState.finished) return fn()
    if (ws._writableState) return ws.end(fn)
    ws.end()
    fn()
  }
  
  var toStreams2 = function(rs) {
    return new (stream.Readable)({objectMode:true, highWaterMark:16}).wrap(rs)
  }
  
  var Duplexify = function(writable, readable, opts) {
    if (!(this instanceof Duplexify)) return new Duplexify(writable, readable, opts)
    stream.Duplex.call(this, opts)
  
    this._writable = null
    this._readable = null
    this._readable2 = null
  
    this._autoDestroy = !opts || opts.autoDestroy !== false
    this._forwardDestroy = !opts || opts.destroy !== false
    this._forwardEnd = !opts || opts.end !== false
    this._corked = 1 // start corked
    this._ondrain = null
    this._drained = false
    this._forwarding = false
    this._unwrite = null
    this._unread = null
    this._ended = false
  
    this.destroyed = false
  
    if (writable) this.setWritable(writable)
    if (readable) this.setReadable(readable)
  }
  
  inherits(Duplexify, stream.Duplex)
  
  Duplexify.obj = function(writable, readable, opts) {
    if (!opts) opts = {}
    opts.objectMode = true
    opts.highWaterMark = 16
    return new Duplexify(writable, readable, opts)
  }
  
  Duplexify.prototype.cork = function() {
    if (++this._corked === 1) this.emit('cork')
  }
  
  Duplexify.prototype.uncork = function() {
    if (this._corked && --this._corked === 0) this.emit('uncork')
  }
  
  Duplexify.prototype.setWritable = function(writable) {
    if (this._unwrite) this._unwrite()
  
    if (this.destroyed) {
      if (writable && writable.destroy) writable.destroy()
      return
    }
  
    if (writable === null || writable === false) {
      this.end()
      return
    }
  
    var self = this
    var unend = eos(writable, {writable:true, readable:false}, destroyer(this, this._forwardEnd))
  
    var ondrain = function() {
      var ondrain = self._ondrain
      self._ondrain = null
      if (ondrain) ondrain()
    }
  
    var clear = function() {
      self._writable.removeListener('drain', ondrain)
      unend()
    }
  
    if (this._unwrite) process.nextTick(ondrain) // force a drain on stream reset to avoid livelocks
  
    this._writable = writable
    this._writable.on('drain', ondrain)
    this._unwrite = clear
  
    this.uncork() // always uncork setWritable
  }
  
  Duplexify.prototype.setReadable = function(readable) {
    if (this._unread) this._unread()
  
    if (this.destroyed) {
      if (readable && readable.destroy) readable.destroy()
      return
    }
  
    if (readable === null || readable === false) {
      this.push(null)
      this.resume()
      return
    }
  
    var self = this
    var unend = eos(readable, {writable:false, readable:true}, destroyer(this))
  
    var onreadable = function() {
      self._forward()
    }
  
    var onend = function() {
      self.push(null)
    }
  
    var clear = function() {
      self._readable2.removeListener('readable', onreadable)
      self._readable2.removeListener('end', onend)
      unend()
    }
  
    this._drained = true
    this._readable = readable
    this._readable2 = readable._readableState ? readable : toStreams2(readable)
    this._readable2.on('readable', onreadable)
    this._readable2.on('end', onend)
    this._unread = clear
  
    this._forward()
  }
  
  Duplexify.prototype._read = function() {
    this._drained = true
    this._forward()
  }
  
  Duplexify.prototype._forward = function() {
    if (this._forwarding || !this._readable2 || !this._drained) return
    this._forwarding = true
  
    var data
  
    while (this._drained && (data = shift(this._readable2)) !== null) {
      if (this.destroyed) continue
      this._drained = this.push(data)
    }
  
    this._forwarding = false
  }
  
  Duplexify.prototype.destroy = function(err) {
    if (this.destroyed) return
    this.destroyed = true
  
    var self = this
    process.nextTick(function() {
      self._destroy(err)
    })
  }
  
  Duplexify.prototype._destroy = function(err) {
    if (err) {
      var ondrain = this._ondrain
      this._ondrain = null
      if (ondrain) ondrain(err)
      else this.emit('error', err)
    }
  
    if (this._forwardDestroy) {
      if (this._readable && this._readable.destroy) this._readable.destroy()
      if (this._writable && this._writable.destroy) this._writable.destroy()
    }
  
    this.emit('close')
  }
  
  Duplexify.prototype._write = function(data, enc, cb) {
    if (this.destroyed) return cb()
    if (this._corked) return onuncork(this, this._write.bind(this, data, enc, cb))
    if (data === SIGNAL_FLUSH) return this._finish(cb)
    if (!this._writable) return cb()
  
    if (this._writable.write(data) === false) this._ondrain = cb
    else cb()
  }
  
  Duplexify.prototype._finish = function(cb) {
    var self = this
    this.emit('preend')
    onuncork(this, function() {
      end(self._forwardEnd && self._writable, function() {
        // haxx to not emit prefinish twice
        if (self._writableState.prefinished === false) self._writableState.prefinished = true
        self.emit('prefinish')
        onuncork(self, cb)
      })
    })
  }
  
  Duplexify.prototype.end = function(data, enc, cb) {
    if (typeof data === 'function') return this.end(null, null, data)
    if (typeof enc === 'function') return this.end(data, null, enc)
    this._ended = true
    if (data) this.write(data)
    if (!this._writableState.ending) this.write(SIGNAL_FLUSH)
    return stream.Writable.prototype.end.call(this, cb)
  }
  
  module.exports = Duplexify
  
  }).call(this,require('_process'),require("buffer").Buffer)
  },{"_process":44,"buffer":12,"end-of-stream":26,"inherits":29,"readable-stream":25,"stream-shift":62}],17:[function(require,module,exports){
  // Copyright Joyent, Inc. and other Node contributors.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a
  // copy of this software and associated documentation files (the
  // "Software"), to deal in the Software without restriction, including
  // without limitation the rights to use, copy, modify, merge, publish,
  // distribute, sublicense, and/or sell copies of the Software, and to permit
  // persons to whom the Software is furnished to do so, subject to the
  // following conditions:
  //
  // The above copyright notice and this permission notice shall be included
  // in all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
  // NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
  // DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  // USE OR OTHER DEALINGS IN THE SOFTWARE.
  
  // a duplex stream is just a stream that is both readable and writable.
  // Since JS doesn't have multiple prototypal inheritance, this class
  // prototypally inherits from Readable, and then parasitically from
  // Writable.
  
  'use strict';
  
  /*<replacement>*/
  
  var pna = require('process-nextick-args');
  /*</replacement>*/
  
  /*<replacement>*/
  var objectKeys = Object.keys || function (obj) {
    var keys = [];
    for (var key in obj) {
      keys.push(key);
    }return keys;
  };
  /*</replacement>*/
  
  module.exports = Duplex;
  
  /*<replacement>*/
  var util = Object.create(require('core-util-is'));
  util.inherits = require('inherits');
  /*</replacement>*/
  
  var Readable = require('./_stream_readable');
  var Writable = require('./_stream_writable');
  
  util.inherits(Duplex, Readable);
  
  {
    // avoid scope creep, the keys array can then be collected
    var keys = objectKeys(Writable.prototype);
    for (var v = 0; v < keys.length; v++) {
      var method = keys[v];
      if (!Duplex.prototype[method]) Duplex.prototype[method] = Writable.prototype[method];
    }
  }
  
  function Duplex(options) {
    if (!(this instanceof Duplex)) return new Duplex(options);
  
    Readable.call(this, options);
    Writable.call(this, options);
  
    if (options && options.readable === false) this.readable = false;
  
    if (options && options.writable === false) this.writable = false;
  
    this.allowHalfOpen = true;
    if (options && options.allowHalfOpen === false) this.allowHalfOpen = false;
  
    this.once('end', onend);
  }
  
  Object.defineProperty(Duplex.prototype, 'writableHighWaterMark', {
    // making it explicit this property is not enumerable
    // because otherwise some prototype manipulation in
    // userland will fail
    enumerable: false,
    get: function () {
      return this._writableState.highWaterMark;
    }
  });
  
  // the no-half-open enforcer
  function onend() {
    // if we allow half-open state, or if the writable side ended,
    // then we're ok.
    if (this.allowHalfOpen || this._writableState.ended) return;
  
    // no more data can be written.
    // But allow more writes to happen in this tick.
    pna.nextTick(onEndNT, this);
  }
  
  function onEndNT(self) {
    self.end();
  }
  
  Object.defineProperty(Duplex.prototype, 'destroyed', {
    get: function () {
      if (this._readableState === undefined || this._writableState === undefined) {
        return false;
      }
      return this._readableState.destroyed && this._writableState.destroyed;
    },
    set: function (value) {
      // we ignore the value if the stream
      // has not been initialized yet
      if (this._readableState === undefined || this._writableState === undefined) {
        return;
      }
  
      // backward compatibility, the user is explicitly
      // managing destroyed
      this._readableState.destroyed = value;
      this._writableState.destroyed = value;
    }
  });
  
  Duplex.prototype._destroy = function (err, cb) {
    this.push(null);
    this.end();
  
    pna.nextTick(cb, err);
  };
  },{"./_stream_readable":19,"./_stream_writable":21,"core-util-is":13,"inherits":29,"process-nextick-args":43}],18:[function(require,module,exports){
  // Copyright Joyent, Inc. and other Node contributors.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a
  // copy of this software and associated documentation files (the
  // "Software"), to deal in the Software without restriction, including
  // without limitation the rights to use, copy, modify, merge, publish,
  // distribute, sublicense, and/or sell copies of the Software, and to permit
  // persons to whom the Software is furnished to do so, subject to the
  // following conditions:
  //
  // The above copyright notice and this permission notice shall be included
  // in all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
  // NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
  // DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  // USE OR OTHER DEALINGS IN THE SOFTWARE.
  
  // a passthrough stream.
  // basically just the most minimal sort of Transform stream.
  // Every written chunk gets output as-is.
  
  'use strict';
  
  module.exports = PassThrough;
  
  var Transform = require('./_stream_transform');
  
  /*<replacement>*/
  var util = Object.create(require('core-util-is'));
  util.inherits = require('inherits');
  /*</replacement>*/
  
  util.inherits(PassThrough, Transform);
  
  function PassThrough(options) {
    if (!(this instanceof PassThrough)) return new PassThrough(options);
  
    Transform.call(this, options);
  }
  
  PassThrough.prototype._transform = function (chunk, encoding, cb) {
    cb(null, chunk);
  };
  },{"./_stream_transform":20,"core-util-is":13,"inherits":29}],19:[function(require,module,exports){
  (function (process,global){
  // Copyright Joyent, Inc. and other Node contributors.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a
  // copy of this software and associated documentation files (the
  // "Software"), to deal in the Software without restriction, including
  // without limitation the rights to use, copy, modify, merge, publish,
  // distribute, sublicense, and/or sell copies of the Software, and to permit
  // persons to whom the Software is furnished to do so, subject to the
  // following conditions:
  //
  // The above copyright notice and this permission notice shall be included
  // in all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
  // NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
  // DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  // USE OR OTHER DEALINGS IN THE SOFTWARE.
  
  'use strict';
  
  /*<replacement>*/
  
  var pna = require('process-nextick-args');
  /*</replacement>*/
  
  module.exports = Readable;
  
  /*<replacement>*/
  var isArray = require('isarray');
  /*</replacement>*/
  
  /*<replacement>*/
  var Duplex;
  /*</replacement>*/
  
  Readable.ReadableState = ReadableState;
  
  /*<replacement>*/
  var EE = require('events').EventEmitter;
  
  var EElistenerCount = function (emitter, type) {
    return emitter.listeners(type).length;
  };
  /*</replacement>*/
  
  /*<replacement>*/
  var Stream = require('./internal/streams/stream');
  /*</replacement>*/
  
  /*<replacement>*/
  
  var Buffer = require('safe-buffer').Buffer;
  var OurUint8Array = global.Uint8Array || function () {};
  function _uint8ArrayToBuffer(chunk) {
    return Buffer.from(chunk);
  }
  function _isUint8Array(obj) {
    return Buffer.isBuffer(obj) || obj instanceof OurUint8Array;
  }
  
  /*</replacement>*/
  
  /*<replacement>*/
  var util = Object.create(require('core-util-is'));
  util.inherits = require('inherits');
  /*</replacement>*/
  
  /*<replacement>*/
  var debugUtil = require('util');
  var debug = void 0;
  if (debugUtil && debugUtil.debuglog) {
    debug = debugUtil.debuglog('stream');
  } else {
    debug = function () {};
  }
  /*</replacement>*/
  
  var BufferList = require('./internal/streams/BufferList');
  var destroyImpl = require('./internal/streams/destroy');
  var StringDecoder;
  
  util.inherits(Readable, Stream);
  
  var kProxyEvents = ['error', 'close', 'destroy', 'pause', 'resume'];
  
  function prependListener(emitter, event, fn) {
    // Sadly this is not cacheable as some libraries bundle their own
    // event emitter implementation with them.
    if (typeof emitter.prependListener === 'function') return emitter.prependListener(event, fn);
  
    // This is a hack to make sure that our error handler is attached before any
    // userland ones.  NEVER DO THIS. This is here only because this code needs
    // to continue to work with older versions of Node.js that do not include
    // the prependListener() method. The goal is to eventually remove this hack.
    if (!emitter._events || !emitter._events[event]) emitter.on(event, fn);else if (isArray(emitter._events[event])) emitter._events[event].unshift(fn);else emitter._events[event] = [fn, emitter._events[event]];
  }
  
  function ReadableState(options, stream) {
    Duplex = Duplex || require('./_stream_duplex');
  
    options = options || {};
  
    // Duplex streams are both readable and writable, but share
    // the same options object.
    // However, some cases require setting options to different
    // values for the readable and the writable sides of the duplex stream.
    // These options can be provided separately as readableXXX and writableXXX.
    var isDuplex = stream instanceof Duplex;
  
    // object stream flag. Used to make read(n) ignore n and to
    // make all the buffer merging and length checks go away
    this.objectMode = !!options.objectMode;
  
    if (isDuplex) this.objectMode = this.objectMode || !!options.readableObjectMode;
  
    // the point at which it stops calling _read() to fill the buffer
    // Note: 0 is a valid value, means "don't call _read preemptively ever"
    var hwm = options.highWaterMark;
    var readableHwm = options.readableHighWaterMark;
    var defaultHwm = this.objectMode ? 16 : 16 * 1024;
  
    if (hwm || hwm === 0) this.highWaterMark = hwm;else if (isDuplex && (readableHwm || readableHwm === 0)) this.highWaterMark = readableHwm;else this.highWaterMark = defaultHwm;
  
    // cast to ints.
    this.highWaterMark = Math.floor(this.highWaterMark);
  
    // A linked list is used to store data chunks instead of an array because the
    // linked list can remove elements from the beginning faster than
    // array.shift()
    this.buffer = new BufferList();
    this.length = 0;
    this.pipes = null;
    this.pipesCount = 0;
    this.flowing = null;
    this.ended = false;
    this.endEmitted = false;
    this.reading = false;
  
    // a flag to be able to tell if the event 'readable'/'data' is emitted
    // immediately, or on a later tick.  We set this to true at first, because
    // any actions that shouldn't happen until "later" should generally also
    // not happen before the first read call.
    this.sync = true;
  
    // whenever we return null, then we set a flag to say
    // that we're awaiting a 'readable' event emission.
    this.needReadable = false;
    this.emittedReadable = false;
    this.readableListening = false;
    this.resumeScheduled = false;
  
    // has it been destroyed
    this.destroyed = false;
  
    // Crypto is kind of old and crusty.  Historically, its default string
    // encoding is 'binary' so we have to make this configurable.
    // Everything else in the universe uses 'utf8', though.
    this.defaultEncoding = options.defaultEncoding || 'utf8';
  
    // the number of writers that are awaiting a drain event in .pipe()s
    this.awaitDrain = 0;
  
    // if true, a maybeReadMore has been scheduled
    this.readingMore = false;
  
    this.decoder = null;
    this.encoding = null;
    if (options.encoding) {
      if (!StringDecoder) StringDecoder = require('string_decoder/').StringDecoder;
      this.decoder = new StringDecoder(options.encoding);
      this.encoding = options.encoding;
    }
  }
  
  function Readable(options) {
    Duplex = Duplex || require('./_stream_duplex');
  
    if (!(this instanceof Readable)) return new Readable(options);
  
    this._readableState = new ReadableState(options, this);
  
    // legacy
    this.readable = true;
  
    if (options) {
      if (typeof options.read === 'function') this._read = options.read;
  
      if (typeof options.destroy === 'function') this._destroy = options.destroy;
    }
  
    Stream.call(this);
  }
  
  Object.defineProperty(Readable.prototype, 'destroyed', {
    get: function () {
      if (this._readableState === undefined) {
        return false;
      }
      return this._readableState.destroyed;
    },
    set: function (value) {
      // we ignore the value if the stream
      // has not been initialized yet
      if (!this._readableState) {
        return;
      }
  
      // backward compatibility, the user is explicitly
      // managing destroyed
      this._readableState.destroyed = value;
    }
  });
  
  Readable.prototype.destroy = destroyImpl.destroy;
  Readable.prototype._undestroy = destroyImpl.undestroy;
  Readable.prototype._destroy = function (err, cb) {
    this.push(null);
    cb(err);
  };
  
  // Manually shove something into the read() buffer.
  // This returns true if the highWaterMark has not been hit yet,
  // similar to how Writable.write() returns true if you should
  // write() some more.
  Readable.prototype.push = function (chunk, encoding) {
    var state = this._readableState;
    var skipChunkCheck;
  
    if (!state.objectMode) {
      if (typeof chunk === 'string') {
        encoding = encoding || state.defaultEncoding;
        if (encoding !== state.encoding) {
          chunk = Buffer.from(chunk, encoding);
          encoding = '';
        }
        skipChunkCheck = true;
      }
    } else {
      skipChunkCheck = true;
    }
  
    return readableAddChunk(this, chunk, encoding, false, skipChunkCheck);
  };
  
  // Unshift should *always* be something directly out of read()
  Readable.prototype.unshift = function (chunk) {
    return readableAddChunk(this, chunk, null, true, false);
  };
  
  function readableAddChunk(stream, chunk, encoding, addToFront, skipChunkCheck) {
    var state = stream._readableState;
    if (chunk === null) {
      state.reading = false;
      onEofChunk(stream, state);
    } else {
      var er;
      if (!skipChunkCheck) er = chunkInvalid(state, chunk);
      if (er) {
        stream.emit('error', er);
      } else if (state.objectMode || chunk && chunk.length > 0) {
        if (typeof chunk !== 'string' && !state.objectMode && Object.getPrototypeOf(chunk) !== Buffer.prototype) {
          chunk = _uint8ArrayToBuffer(chunk);
        }
  
        if (addToFront) {
          if (state.endEmitted) stream.emit('error', new Error('stream.unshift() after end event'));else addChunk(stream, state, chunk, true);
        } else if (state.ended) {
          stream.emit('error', new Error('stream.push() after EOF'));
        } else {
          state.reading = false;
          if (state.decoder && !encoding) {
            chunk = state.decoder.write(chunk);
            if (state.objectMode || chunk.length !== 0) addChunk(stream, state, chunk, false);else maybeReadMore(stream, state);
          } else {
            addChunk(stream, state, chunk, false);
          }
        }
      } else if (!addToFront) {
        state.reading = false;
      }
    }
  
    return needMoreData(state);
  }
  
  function addChunk(stream, state, chunk, addToFront) {
    if (state.flowing && state.length === 0 && !state.sync) {
      stream.emit('data', chunk);
      stream.read(0);
    } else {
      // update the buffer info.
      state.length += state.objectMode ? 1 : chunk.length;
      if (addToFront) state.buffer.unshift(chunk);else state.buffer.push(chunk);
  
      if (state.needReadable) emitReadable(stream);
    }
    maybeReadMore(stream, state);
  }
  
  function chunkInvalid(state, chunk) {
    var er;
    if (!_isUint8Array(chunk) && typeof chunk !== 'string' && chunk !== undefined && !state.objectMode) {
      er = new TypeError('Invalid non-string/buffer chunk');
    }
    return er;
  }
  
  // if it's past the high water mark, we can push in some more.
  // Also, if we have no data yet, we can stand some
  // more bytes.  This is to work around cases where hwm=0,
  // such as the repl.  Also, if the push() triggered a
  // readable event, and the user called read(largeNumber) such that
  // needReadable was set, then we ought to push more, so that another
  // 'readable' event will be triggered.
  function needMoreData(state) {
    return !state.ended && (state.needReadable || state.length < state.highWaterMark || state.length === 0);
  }
  
  Readable.prototype.isPaused = function () {
    return this._readableState.flowing === false;
  };
  
  // backwards compatibility.
  Readable.prototype.setEncoding = function (enc) {
    if (!StringDecoder) StringDecoder = require('string_decoder/').StringDecoder;
    this._readableState.decoder = new StringDecoder(enc);
    this._readableState.encoding = enc;
    return this;
  };
  
  // Don't raise the hwm > 8MB
  var MAX_HWM = 0x800000;
  function computeNewHighWaterMark(n) {
    if (n >= MAX_HWM) {
      n = MAX_HWM;
    } else {
      // Get the next highest power of 2 to prevent increasing hwm excessively in
      // tiny amounts
      n--;
      n |= n >>> 1;
      n |= n >>> 2;
      n |= n >>> 4;
      n |= n >>> 8;
      n |= n >>> 16;
      n++;
    }
    return n;
  }
  
  // This function is designed to be inlinable, so please take care when making
  // changes to the function body.
  function howMuchToRead(n, state) {
    if (n <= 0 || state.length === 0 && state.ended) return 0;
    if (state.objectMode) return 1;
    if (n !== n) {
      // Only flow one buffer at a time
      if (state.flowing && state.length) return state.buffer.head.data.length;else return state.length;
    }
    // If we're asking for more than the current hwm, then raise the hwm.
    if (n > state.highWaterMark) state.highWaterMark = computeNewHighWaterMark(n);
    if (n <= state.length) return n;
    // Don't have enough
    if (!state.ended) {
      state.needReadable = true;
      return 0;
    }
    return state.length;
  }
  
  // you can override either this method, or the async _read(n) below.
  Readable.prototype.read = function (n) {
    debug('read', n);
    n = parseInt(n, 10);
    var state = this._readableState;
    var nOrig = n;
  
    if (n !== 0) state.emittedReadable = false;
  
    // if we're doing read(0) to trigger a readable event, but we
    // already have a bunch of data in the buffer, then just trigger
    // the 'readable' event and move on.
    if (n === 0 && state.needReadable && (state.length >= state.highWaterMark || state.ended)) {
      debug('read: emitReadable', state.length, state.ended);
      if (state.length === 0 && state.ended) endReadable(this);else emitReadable(this);
      return null;
    }
  
    n = howMuchToRead(n, state);
  
    // if we've ended, and we're now clear, then finish it up.
    if (n === 0 && state.ended) {
      if (state.length === 0) endReadable(this);
      return null;
    }
  
    // All the actual chunk generation logic needs to be
    // *below* the call to _read.  The reason is that in certain
    // synthetic stream cases, such as passthrough streams, _read
    // may be a completely synchronous operation which may change
    // the state of the read buffer, providing enough data when
    // before there was *not* enough.
    //
    // So, the steps are:
    // 1. Figure out what the state of things will be after we do
    // a read from the buffer.
    //
    // 2. If that resulting state will trigger a _read, then call _read.
    // Note that this may be asynchronous, or synchronous.  Yes, it is
    // deeply ugly to write APIs this way, but that still doesn't mean
    // that the Readable class should behave improperly, as streams are
    // designed to be sync/async agnostic.
    // Take note if the _read call is sync or async (ie, if the read call
    // has returned yet), so that we know whether or not it's safe to emit
    // 'readable' etc.
    //
    // 3. Actually pull the requested chunks out of the buffer and return.
  
    // if we need a readable event, then we need to do some reading.
    var doRead = state.needReadable;
    debug('need readable', doRead);
  
    // if we currently have less than the highWaterMark, then also read some
    if (state.length === 0 || state.length - n < state.highWaterMark) {
      doRead = true;
      debug('length less than watermark', doRead);
    }
  
    // however, if we've ended, then there's no point, and if we're already
    // reading, then it's unnecessary.
    if (state.ended || state.reading) {
      doRead = false;
      debug('reading or ended', doRead);
    } else if (doRead) {
      debug('do read');
      state.reading = true;
      state.sync = true;
      // if the length is currently zero, then we *need* a readable event.
      if (state.length === 0) state.needReadable = true;
      // call internal read method
      this._read(state.highWaterMark);
      state.sync = false;
      // If _read pushed data synchronously, then `reading` will be false,
      // and we need to re-evaluate how much data we can return to the user.
      if (!state.reading) n = howMuchToRead(nOrig, state);
    }
  
    var ret;
    if (n > 0) ret = fromList(n, state);else ret = null;
  
    if (ret === null) {
      state.needReadable = true;
      n = 0;
    } else {
      state.length -= n;
    }
  
    if (state.length === 0) {
      // If we have nothing in the buffer, then we want to know
      // as soon as we *do* get something into the buffer.
      if (!state.ended) state.needReadable = true;
  
      // If we tried to read() past the EOF, then emit end on the next tick.
      if (nOrig !== n && state.ended) endReadable(this);
    }
  
    if (ret !== null) this.emit('data', ret);
  
    return ret;
  };
  
  function onEofChunk(stream, state) {
    if (state.ended) return;
    if (state.decoder) {
      var chunk = state.decoder.end();
      if (chunk && chunk.length) {
        state.buffer.push(chunk);
        state.length += state.objectMode ? 1 : chunk.length;
      }
    }
    state.ended = true;
  
    // emit 'readable' now to make sure it gets picked up.
    emitReadable(stream);
  }
  
  // Don't emit readable right away in sync mode, because this can trigger
  // another read() call => stack overflow.  This way, it might trigger
  // a nextTick recursion warning, but that's not so bad.
  function emitReadable(stream) {
    var state = stream._readableState;
    state.needReadable = false;
    if (!state.emittedReadable) {
      debug('emitReadable', state.flowing);
      state.emittedReadable = true;
      if (state.sync) pna.nextTick(emitReadable_, stream);else emitReadable_(stream);
    }
  }
  
  function emitReadable_(stream) {
    debug('emit readable');
    stream.emit('readable');
    flow(stream);
  }
  
  // at this point, the user has presumably seen the 'readable' event,
  // and called read() to consume some data.  that may have triggered
  // in turn another _read(n) call, in which case reading = true if
  // it's in progress.
  // However, if we're not ended, or reading, and the length < hwm,
  // then go ahead and try to read some more preemptively.
  function maybeReadMore(stream, state) {
    if (!state.readingMore) {
      state.readingMore = true;
      pna.nextTick(maybeReadMore_, stream, state);
    }
  }
  
  function maybeReadMore_(stream, state) {
    var len = state.length;
    while (!state.reading && !state.flowing && !state.ended && state.length < state.highWaterMark) {
      debug('maybeReadMore read 0');
      stream.read(0);
      if (len === state.length)
        // didn't get any data, stop spinning.
        break;else len = state.length;
    }
    state.readingMore = false;
  }
  
  // abstract method.  to be overridden in specific implementation classes.
  // call cb(er, data) where data is <= n in length.
  // for virtual (non-string, non-buffer) streams, "length" is somewhat
  // arbitrary, and perhaps not very meaningful.
  Readable.prototype._read = function (n) {
    this.emit('error', new Error('_read() is not implemented'));
  };
  
  Readable.prototype.pipe = function (dest, pipeOpts) {
    var src = this;
    var state = this._readableState;
  
    switch (state.pipesCount) {
      case 0:
        state.pipes = dest;
        break;
      case 1:
        state.pipes = [state.pipes, dest];
        break;
      default:
        state.pipes.push(dest);
        break;
    }
    state.pipesCount += 1;
    debug('pipe count=%d opts=%j', state.pipesCount, pipeOpts);
  
    var doEnd = (!pipeOpts || pipeOpts.end !== false) && dest !== process.stdout && dest !== process.stderr;
  
    var endFn = doEnd ? onend : unpipe;
    if (state.endEmitted) pna.nextTick(endFn);else src.once('end', endFn);
  
    dest.on('unpipe', onunpipe);
    function onunpipe(readable, unpipeInfo) {
      debug('onunpipe');
      if (readable === src) {
        if (unpipeInfo && unpipeInfo.hasUnpiped === false) {
          unpipeInfo.hasUnpiped = true;
          cleanup();
        }
      }
    }
  
    function onend() {
      debug('onend');
      dest.end();
    }
  
    // when the dest drains, it reduces the awaitDrain counter
    // on the source.  This would be more elegant with a .once()
    // handler in flow(), but adding and removing repeatedly is
    // too slow.
    var ondrain = pipeOnDrain(src);
    dest.on('drain', ondrain);
  
    var cleanedUp = false;
    function cleanup() {
      debug('cleanup');
      // cleanup event handlers once the pipe is broken
      dest.removeListener('close', onclose);
      dest.removeListener('finish', onfinish);
      dest.removeListener('drain', ondrain);
      dest.removeListener('error', onerror);
      dest.removeListener('unpipe', onunpipe);
      src.removeListener('end', onend);
      src.removeListener('end', unpipe);
      src.removeListener('data', ondata);
  
      cleanedUp = true;
  
      // if the reader is waiting for a drain event from this
      // specific writer, then it would cause it to never start
      // flowing again.
      // So, if this is awaiting a drain, then we just call it now.
      // If we don't know, then assume that we are waiting for one.
      if (state.awaitDrain && (!dest._writableState || dest._writableState.needDrain)) ondrain();
    }
  
    // If the user pushes more data while we're writing to dest then we'll end up
    // in ondata again. However, we only want to increase awaitDrain once because
    // dest will only emit one 'drain' event for the multiple writes.
    // => Introduce a guard on increasing awaitDrain.
    var increasedAwaitDrain = false;
    src.on('data', ondata);
    function ondata(chunk) {
      debug('ondata');
      increasedAwaitDrain = false;
      var ret = dest.write(chunk);
      if (false === ret && !increasedAwaitDrain) {
        // If the user unpiped during `dest.write()`, it is possible
        // to get stuck in a permanently paused state if that write
        // also returned false.
        // => Check whether `dest` is still a piping destination.
        if ((state.pipesCount === 1 && state.pipes === dest || state.pipesCount > 1 && indexOf(state.pipes, dest) !== -1) && !cleanedUp) {
          debug('false write response, pause', src._readableState.awaitDrain);
          src._readableState.awaitDrain++;
          increasedAwaitDrain = true;
        }
        src.pause();
      }
    }
  
    // if the dest has an error, then stop piping into it.
    // however, don't suppress the throwing behavior for this.
    function onerror(er) {
      debug('onerror', er);
      unpipe();
      dest.removeListener('error', onerror);
      if (EElistenerCount(dest, 'error') === 0) dest.emit('error', er);
    }
  
    // Make sure our error handler is attached before userland ones.
    prependListener(dest, 'error', onerror);
  
    // Both close and finish should trigger unpipe, but only once.
    function onclose() {
      dest.removeListener('finish', onfinish);
      unpipe();
    }
    dest.once('close', onclose);
    function onfinish() {
      debug('onfinish');
      dest.removeListener('close', onclose);
      unpipe();
    }
    dest.once('finish', onfinish);
  
    function unpipe() {
      debug('unpipe');
      src.unpipe(dest);
    }
  
    // tell the dest that it's being piped to
    dest.emit('pipe', src);
  
    // start the flow if it hasn't been started already.
    if (!state.flowing) {
      debug('pipe resume');
      src.resume();
    }
  
    return dest;
  };
  
  function pipeOnDrain(src) {
    return function () {
      var state = src._readableState;
      debug('pipeOnDrain', state.awaitDrain);
      if (state.awaitDrain) state.awaitDrain--;
      if (state.awaitDrain === 0 && EElistenerCount(src, 'data')) {
        state.flowing = true;
        flow(src);
      }
    };
  }
  
  Readable.prototype.unpipe = function (dest) {
    var state = this._readableState;
    var unpipeInfo = { hasUnpiped: false };
  
    // if we're not piping anywhere, then do nothing.
    if (state.pipesCount === 0) return this;
  
    // just one destination.  most common case.
    if (state.pipesCount === 1) {
      // passed in one, but it's not the right one.
      if (dest && dest !== state.pipes) return this;
  
      if (!dest) dest = state.pipes;
  
      // got a match.
      state.pipes = null;
      state.pipesCount = 0;
      state.flowing = false;
      if (dest) dest.emit('unpipe', this, unpipeInfo);
      return this;
    }
  
    // slow case. multiple pipe destinations.
  
    if (!dest) {
      // remove all.
      var dests = state.pipes;
      var len = state.pipesCount;
      state.pipes = null;
      state.pipesCount = 0;
      state.flowing = false;
  
      for (var i = 0; i < len; i++) {
        dests[i].emit('unpipe', this, unpipeInfo);
      }return this;
    }
  
    // try to find the right one.
    var index = indexOf(state.pipes, dest);
    if (index === -1) return this;
  
    state.pipes.splice(index, 1);
    state.pipesCount -= 1;
    if (state.pipesCount === 1) state.pipes = state.pipes[0];
  
    dest.emit('unpipe', this, unpipeInfo);
  
    return this;
  };
  
  // set up data events if they are asked for
  // Ensure readable listeners eventually get something
  Readable.prototype.on = function (ev, fn) {
    var res = Stream.prototype.on.call(this, ev, fn);
  
    if (ev === 'data') {
      // Start flowing on next tick if stream isn't explicitly paused
      if (this._readableState.flowing !== false) this.resume();
    } else if (ev === 'readable') {
      var state = this._readableState;
      if (!state.endEmitted && !state.readableListening) {
        state.readableListening = state.needReadable = true;
        state.emittedReadable = false;
        if (!state.reading) {
          pna.nextTick(nReadingNextTick, this);
        } else if (state.length) {
          emitReadable(this);
        }
      }
    }
  
    return res;
  };
  Readable.prototype.addListener = Readable.prototype.on;
  
  function nReadingNextTick(self) {
    debug('readable nexttick read 0');
    self.read(0);
  }
  
  // pause() and resume() are remnants of the legacy readable stream API
  // If the user uses them, then switch into old mode.
  Readable.prototype.resume = function () {
    var state = this._readableState;
    if (!state.flowing) {
      debug('resume');
      state.flowing = true;
      resume(this, state);
    }
    return this;
  };
  
  function resume(stream, state) {
    if (!state.resumeScheduled) {
      state.resumeScheduled = true;
      pna.nextTick(resume_, stream, state);
    }
  }
  
  function resume_(stream, state) {
    if (!state.reading) {
      debug('resume read 0');
      stream.read(0);
    }
  
    state.resumeScheduled = false;
    state.awaitDrain = 0;
    stream.emit('resume');
    flow(stream);
    if (state.flowing && !state.reading) stream.read(0);
  }
  
  Readable.prototype.pause = function () {
    debug('call pause flowing=%j', this._readableState.flowing);
    if (false !== this._readableState.flowing) {
      debug('pause');
      this._readableState.flowing = false;
      this.emit('pause');
    }
    return this;
  };
  
  function flow(stream) {
    var state = stream._readableState;
    debug('flow', state.flowing);
    while (state.flowing && stream.read() !== null) {}
  }
  
  // wrap an old-style stream as the async data source.
  // This is *not* part of the readable stream interface.
  // It is an ugly unfortunate mess of history.
  Readable.prototype.wrap = function (stream) {
    var _this = this;
  
    var state = this._readableState;
    var paused = false;
  
    stream.on('end', function () {
      debug('wrapped end');
      if (state.decoder && !state.ended) {
        var chunk = state.decoder.end();
        if (chunk && chunk.length) _this.push(chunk);
      }
  
      _this.push(null);
    });
  
    stream.on('data', function (chunk) {
      debug('wrapped data');
      if (state.decoder) chunk = state.decoder.write(chunk);
  
      // don't skip over falsy values in objectMode
      if (state.objectMode && (chunk === null || chunk === undefined)) return;else if (!state.objectMode && (!chunk || !chunk.length)) return;
  
      var ret = _this.push(chunk);
      if (!ret) {
        paused = true;
        stream.pause();
      }
    });
  
    // proxy all the other methods.
    // important when wrapping filters and duplexes.
    for (var i in stream) {
      if (this[i] === undefined && typeof stream[i] === 'function') {
        this[i] = function (method) {
          return function () {
            return stream[method].apply(stream, arguments);
          };
        }(i);
      }
    }
  
    // proxy certain important events.
    for (var n = 0; n < kProxyEvents.length; n++) {
      stream.on(kProxyEvents[n], this.emit.bind(this, kProxyEvents[n]));
    }
  
    // when we try to consume some more bytes, simply unpause the
    // underlying stream.
    this._read = function (n) {
      debug('wrapped _read', n);
      if (paused) {
        paused = false;
        stream.resume();
      }
    };
  
    return this;
  };
  
  Object.defineProperty(Readable.prototype, 'readableHighWaterMark', {
    // making it explicit this property is not enumerable
    // because otherwise some prototype manipulation in
    // userland will fail
    enumerable: false,
    get: function () {
      return this._readableState.highWaterMark;
    }
  });
  
  // exposed for testing purposes only.
  Readable._fromList = fromList;
  
  // Pluck off n bytes from an array of buffers.
  // Length is the combined lengths of all the buffers in the list.
  // This function is designed to be inlinable, so please take care when making
  // changes to the function body.
  function fromList(n, state) {
    // nothing buffered
    if (state.length === 0) return null;
  
    var ret;
    if (state.objectMode) ret = state.buffer.shift();else if (!n || n >= state.length) {
      // read it all, truncate the list
      if (state.decoder) ret = state.buffer.join('');else if (state.buffer.length === 1) ret = state.buffer.head.data;else ret = state.buffer.concat(state.length);
      state.buffer.clear();
    } else {
      // read part of list
      ret = fromListPartial(n, state.buffer, state.decoder);
    }
  
    return ret;
  }
  
  // Extracts only enough buffered data to satisfy the amount requested.
  // This function is designed to be inlinable, so please take care when making
  // changes to the function body.
  function fromListPartial(n, list, hasStrings) {
    var ret;
    if (n < list.head.data.length) {
      // slice is the same for buffers and strings
      ret = list.head.data.slice(0, n);
      list.head.data = list.head.data.slice(n);
    } else if (n === list.head.data.length) {
      // first chunk is a perfect match
      ret = list.shift();
    } else {
      // result spans more than one buffer
      ret = hasStrings ? copyFromBufferString(n, list) : copyFromBuffer(n, list);
    }
    return ret;
  }
  
  // Copies a specified amount of characters from the list of buffered data
  // chunks.
  // This function is designed to be inlinable, so please take care when making
  // changes to the function body.
  function copyFromBufferString(n, list) {
    var p = list.head;
    var c = 1;
    var ret = p.data;
    n -= ret.length;
    while (p = p.next) {
      var str = p.data;
      var nb = n > str.length ? str.length : n;
      if (nb === str.length) ret += str;else ret += str.slice(0, n);
      n -= nb;
      if (n === 0) {
        if (nb === str.length) {
          ++c;
          if (p.next) list.head = p.next;else list.head = list.tail = null;
        } else {
          list.head = p;
          p.data = str.slice(nb);
        }
        break;
      }
      ++c;
    }
    list.length -= c;
    return ret;
  }
  
  // Copies a specified amount of bytes from the list of buffered data chunks.
  // This function is designed to be inlinable, so please take care when making
  // changes to the function body.
  function copyFromBuffer(n, list) {
    var ret = Buffer.allocUnsafe(n);
    var p = list.head;
    var c = 1;
    p.data.copy(ret);
    n -= p.data.length;
    while (p = p.next) {
      var buf = p.data;
      var nb = n > buf.length ? buf.length : n;
      buf.copy(ret, ret.length - n, 0, nb);
      n -= nb;
      if (n === 0) {
        if (nb === buf.length) {
          ++c;
          if (p.next) list.head = p.next;else list.head = list.tail = null;
        } else {
          list.head = p;
          p.data = buf.slice(nb);
        }
        break;
      }
      ++c;
    }
    list.length -= c;
    return ret;
  }
  
  function endReadable(stream) {
    var state = stream._readableState;
  
    // If we get here before consuming all the bytes, then that is a
    // bug in node.  Should never happen.
    if (state.length > 0) throw new Error('"endReadable()" called on non-empty stream');
  
    if (!state.endEmitted) {
      state.ended = true;
      pna.nextTick(endReadableNT, state, stream);
    }
  }
  
  function endReadableNT(state, stream) {
    // Check that we didn't get one last unshift.
    if (!state.endEmitted && state.length === 0) {
      state.endEmitted = true;
      stream.readable = false;
      stream.emit('end');
    }
  }
  
  function indexOf(xs, x) {
    for (var i = 0, l = xs.length; i < l; i++) {
      if (xs[i] === x) return i;
    }
    return -1;
  }
  }).call(this,require('_process'),typeof global !== "undefined" ? global : typeof self !== "undefined" ? self : typeof window !== "undefined" ? window : {})
  },{"./_stream_duplex":17,"./internal/streams/BufferList":22,"./internal/streams/destroy":23,"./internal/streams/stream":24,"_process":44,"core-util-is":13,"events":27,"inherits":29,"isarray":31,"process-nextick-args":43,"safe-buffer":61,"string_decoder/":63,"util":11}],20:[function(require,module,exports){
  // Copyright Joyent, Inc. and other Node contributors.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a
  // copy of this software and associated documentation files (the
  // "Software"), to deal in the Software without restriction, including
  // without limitation the rights to use, copy, modify, merge, publish,
  // distribute, sublicense, and/or sell copies of the Software, and to permit
  // persons to whom the Software is furnished to do so, subject to the
  // following conditions:
  //
  // The above copyright notice and this permission notice shall be included
  // in all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
  // NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
  // DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  // USE OR OTHER DEALINGS IN THE SOFTWARE.
  
  // a transform stream is a readable/writable stream where you do
  // something with the data.  Sometimes it's called a "filter",
  // but that's not a great name for it, since that implies a thing where
  // some bits pass through, and others are simply ignored.  (That would
  // be a valid example of a transform, of course.)
  //
  // While the output is causally related to the input, it's not a
  // necessarily symmetric or synchronous transformation.  For example,
  // a zlib stream might take multiple plain-text writes(), and then
  // emit a single compressed chunk some time in the future.
  //
  // Here's how this works:
  //
  // The Transform stream has all the aspects of the readable and writable
  // stream classes.  When you write(chunk), that calls _write(chunk,cb)
  // internally, and returns false if there's a lot of pending writes
  // buffered up.  When you call read(), that calls _read(n) until
  // there's enough pending readable data buffered up.
  //
  // In a transform stream, the written data is placed in a buffer.  When
  // _read(n) is called, it transforms the queued up data, calling the
  // buffered _write cb's as it consumes chunks.  If consuming a single
  // written chunk would result in multiple output chunks, then the first
  // outputted bit calls the readcb, and subsequent chunks just go into
  // the read buffer, and will cause it to emit 'readable' if necessary.
  //
  // This way, back-pressure is actually determined by the reading side,
  // since _read has to be called to start processing a new chunk.  However,
  // a pathological inflate type of transform can cause excessive buffering
  // here.  For example, imagine a stream where every byte of input is
  // interpreted as an integer from 0-255, and then results in that many
  // bytes of output.  Writing the 4 bytes {ff,ff,ff,ff} would result in
  // 1kb of data being output.  In this case, you could write a very small
  // amount of input, and end up with a very large amount of output.  In
  // such a pathological inflating mechanism, there'd be no way to tell
  // the system to stop doing the transform.  A single 4MB write could
  // cause the system to run out of memory.
  //
  // However, even in such a pathological case, only a single written chunk
  // would be consumed, and then the rest would wait (un-transformed) until
  // the results of the previous transformed chunk were consumed.
  
  'use strict';
  
  module.exports = Transform;
  
  var Duplex = require('./_stream_duplex');
  
  /*<replacement>*/
  var util = Object.create(require('core-util-is'));
  util.inherits = require('inherits');
  /*</replacement>*/
  
  util.inherits(Transform, Duplex);
  
  function afterTransform(er, data) {
    var ts = this._transformState;
    ts.transforming = false;
  
    var cb = ts.writecb;
  
    if (!cb) {
      return this.emit('error', new Error('write callback called multiple times'));
    }
  
    ts.writechunk = null;
    ts.writecb = null;
  
    if (data != null) // single equals check for both `null` and `undefined`
      this.push(data);
  
    cb(er);
  
    var rs = this._readableState;
    rs.reading = false;
    if (rs.needReadable || rs.length < rs.highWaterMark) {
      this._read(rs.highWaterMark);
    }
  }
  
  function Transform(options) {
    if (!(this instanceof Transform)) return new Transform(options);
  
    Duplex.call(this, options);
  
    this._transformState = {
      afterTransform: afterTransform.bind(this),
      needTransform: false,
      transforming: false,
      writecb: null,
      writechunk: null,
      writeencoding: null
    };
  
    // start out asking for a readable event once data is transformed.
    this._readableState.needReadable = true;
  
    // we have implemented the _read method, and done the other things
    // that Readable wants before the first _read call, so unset the
    // sync guard flag.
    this._readableState.sync = false;
  
    if (options) {
      if (typeof options.transform === 'function') this._transform = options.transform;
  
      if (typeof options.flush === 'function') this._flush = options.flush;
    }
  
    // When the writable side finishes, then flush out anything remaining.
    this.on('prefinish', prefinish);
  }
  
  function prefinish() {
    var _this = this;
  
    if (typeof this._flush === 'function') {
      this._flush(function (er, data) {
        done(_this, er, data);
      });
    } else {
      done(this, null, null);
    }
  }
  
  Transform.prototype.push = function (chunk, encoding) {
    this._transformState.needTransform = false;
    return Duplex.prototype.push.call(this, chunk, encoding);
  };
  
  // This is the part where you do stuff!
  // override this function in implementation classes.
  // 'chunk' is an input chunk.
  //
  // Call `push(newChunk)` to pass along transformed output
  // to the readable side.  You may call 'push' zero or more times.
  //
  // Call `cb(err)` when you are done with this chunk.  If you pass
  // an error, then that'll put the hurt on the whole operation.  If you
  // never call cb(), then you'll never get another chunk.
  Transform.prototype._transform = function (chunk, encoding, cb) {
    throw new Error('_transform() is not implemented');
  };
  
  Transform.prototype._write = function (chunk, encoding, cb) {
    var ts = this._transformState;
    ts.writecb = cb;
    ts.writechunk = chunk;
    ts.writeencoding = encoding;
    if (!ts.transforming) {
      var rs = this._readableState;
      if (ts.needTransform || rs.needReadable || rs.length < rs.highWaterMark) this._read(rs.highWaterMark);
    }
  };
  
  // Doesn't matter what the args are here.
  // _transform does all the work.
  // That we got here means that the readable side wants more data.
  Transform.prototype._read = function (n) {
    var ts = this._transformState;
  
    if (ts.writechunk !== null && ts.writecb && !ts.transforming) {
      ts.transforming = true;
      this._transform(ts.writechunk, ts.writeencoding, ts.afterTransform);
    } else {
      // mark that we need a transform, so that any data that comes in
      // will get processed, now that we've asked for it.
      ts.needTransform = true;
    }
  };
  
  Transform.prototype._destroy = function (err, cb) {
    var _this2 = this;
  
    Duplex.prototype._destroy.call(this, err, function (err2) {
      cb(err2);
      _this2.emit('close');
    });
  };
  
  function done(stream, er, data) {
    if (er) return stream.emit('error', er);
  
    if (data != null) // single equals check for both `null` and `undefined`
      stream.push(data);
  
    // if there's nothing in the write buffer, then that means
    // that nothing more will ever be provided
    if (stream._writableState.length) throw new Error('Calling transform done when ws.length != 0');
  
    if (stream._transformState.transforming) throw new Error('Calling transform done when still transforming');
  
    return stream.push(null);
  }
  },{"./_stream_duplex":17,"core-util-is":13,"inherits":29}],21:[function(require,module,exports){
  (function (process,global,setImmediate){
  // Copyright Joyent, Inc. and other Node contributors.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a
  // copy of this software and associated documentation files (the
  // "Software"), to deal in the Software without restriction, including
  // without limitation the rights to use, copy, modify, merge, publish,
  // distribute, sublicense, and/or sell copies of the Software, and to permit
  // persons to whom the Software is furnished to do so, subject to the
  // following conditions:
  //
  // The above copyright notice and this permission notice shall be included
  // in all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
  // NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
  // DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  // USE OR OTHER DEALINGS IN THE SOFTWARE.
  
  // A bit simpler than readable streams.
  // Implement an async ._write(chunk, encoding, cb), and it'll handle all
  // the drain event emission and buffering.
  
  'use strict';
  
  /*<replacement>*/
  
  var pna = require('process-nextick-args');
  /*</replacement>*/
  
  module.exports = Writable;
  
  /* <replacement> */
  function WriteReq(chunk, encoding, cb) {
    this.chunk = chunk;
    this.encoding = encoding;
    this.callback = cb;
    this.next = null;
  }
  
  // It seems a linked list but it is not
  // there will be only 2 of these for each stream
  function CorkedRequest(state) {
    var _this = this;
  
    this.next = null;
    this.entry = null;
    this.finish = function () {
      onCorkedFinish(_this, state);
    };
  }
  /* </replacement> */
  
  /*<replacement>*/
  var asyncWrite = !process.browser && ['v0.10', 'v0.9.'].indexOf(process.version.slice(0, 5)) > -1 ? setImmediate : pna.nextTick;
  /*</replacement>*/
  
  /*<replacement>*/
  var Duplex;
  /*</replacement>*/
  
  Writable.WritableState = WritableState;
  
  /*<replacement>*/
  var util = Object.create(require('core-util-is'));
  util.inherits = require('inherits');
  /*</replacement>*/
  
  /*<replacement>*/
  var internalUtil = {
    deprecate: require('util-deprecate')
  };
  /*</replacement>*/
  
  /*<replacement>*/
  var Stream = require('./internal/streams/stream');
  /*</replacement>*/
  
  /*<replacement>*/
  
  var Buffer = require('safe-buffer').Buffer;
  var OurUint8Array = global.Uint8Array || function () {};
  function _uint8ArrayToBuffer(chunk) {
    return Buffer.from(chunk);
  }
  function _isUint8Array(obj) {
    return Buffer.isBuffer(obj) || obj instanceof OurUint8Array;
  }
  
  /*</replacement>*/
  
  var destroyImpl = require('./internal/streams/destroy');
  
  util.inherits(Writable, Stream);
  
  function nop() {}
  
  function WritableState(options, stream) {
    Duplex = Duplex || require('./_stream_duplex');
  
    options = options || {};
  
    // Duplex streams are both readable and writable, but share
    // the same options object.
    // However, some cases require setting options to different
    // values for the readable and the writable sides of the duplex stream.
    // These options can be provided separately as readableXXX and writableXXX.
    var isDuplex = stream instanceof Duplex;
  
    // object stream flag to indicate whether or not this stream
    // contains buffers or objects.
    this.objectMode = !!options.objectMode;
  
    if (isDuplex) this.objectMode = this.objectMode || !!options.writableObjectMode;
  
    // the point at which write() starts returning false
    // Note: 0 is a valid value, means that we always return false if
    // the entire buffer is not flushed immediately on write()
    var hwm = options.highWaterMark;
    var writableHwm = options.writableHighWaterMark;
    var defaultHwm = this.objectMode ? 16 : 16 * 1024;
  
    if (hwm || hwm === 0) this.highWaterMark = hwm;else if (isDuplex && (writableHwm || writableHwm === 0)) this.highWaterMark = writableHwm;else this.highWaterMark = defaultHwm;
  
    // cast to ints.
    this.highWaterMark = Math.floor(this.highWaterMark);
  
    // if _final has been called
    this.finalCalled = false;
  
    // drain event flag.
    this.needDrain = false;
    // at the start of calling end()
    this.ending = false;
    // when end() has been called, and returned
    this.ended = false;
    // when 'finish' is emitted
    this.finished = false;
  
    // has it been destroyed
    this.destroyed = false;
  
    // should we decode strings into buffers before passing to _write?
    // this is here so that some node-core streams can optimize string
    // handling at a lower level.
    var noDecode = options.decodeStrings === false;
    this.decodeStrings = !noDecode;
  
    // Crypto is kind of old and crusty.  Historically, its default string
    // encoding is 'binary' so we have to make this configurable.
    // Everything else in the universe uses 'utf8', though.
    this.defaultEncoding = options.defaultEncoding || 'utf8';
  
    // not an actual buffer we keep track of, but a measurement
    // of how much we're waiting to get pushed to some underlying
    // socket or file.
    this.length = 0;
  
    // a flag to see when we're in the middle of a write.
    this.writing = false;
  
    // when true all writes will be buffered until .uncork() call
    this.corked = 0;
  
    // a flag to be able to tell if the onwrite cb is called immediately,
    // or on a later tick.  We set this to true at first, because any
    // actions that shouldn't happen until "later" should generally also
    // not happen before the first write call.
    this.sync = true;
  
    // a flag to know if we're processing previously buffered items, which
    // may call the _write() callback in the same tick, so that we don't
    // end up in an overlapped onwrite situation.
    this.bufferProcessing = false;
  
    // the callback that's passed to _write(chunk,cb)
    this.onwrite = function (er) {
      onwrite(stream, er);
    };
  
    // the callback that the user supplies to write(chunk,encoding,cb)
    this.writecb = null;
  
    // the amount that is being written when _write is called.
    this.writelen = 0;
  
    this.bufferedRequest = null;
    this.lastBufferedRequest = null;
  
    // number of pending user-supplied write callbacks
    // this must be 0 before 'finish' can be emitted
    this.pendingcb = 0;
  
    // emit prefinish if the only thing we're waiting for is _write cbs
    // This is relevant for synchronous Transform streams
    this.prefinished = false;
  
    // True if the error was already emitted and should not be thrown again
    this.errorEmitted = false;
  
    // count buffered requests
    this.bufferedRequestCount = 0;
  
    // allocate the first CorkedRequest, there is always
    // one allocated and free to use, and we maintain at most two
    this.corkedRequestsFree = new CorkedRequest(this);
  }
  
  WritableState.prototype.getBuffer = function getBuffer() {
    var current = this.bufferedRequest;
    var out = [];
    while (current) {
      out.push(current);
      current = current.next;
    }
    return out;
  };
  
  (function () {
    try {
      Object.defineProperty(WritableState.prototype, 'buffer', {
        get: internalUtil.deprecate(function () {
          return this.getBuffer();
        }, '_writableState.buffer is deprecated. Use _writableState.getBuffer ' + 'instead.', 'DEP0003')
      });
    } catch (_) {}
  })();
  
  // Test _writableState for inheritance to account for Duplex streams,
  // whose prototype chain only points to Readable.
  var realHasInstance;
  if (typeof Symbol === 'function' && Symbol.hasInstance && typeof Function.prototype[Symbol.hasInstance] === 'function') {
    realHasInstance = Function.prototype[Symbol.hasInstance];
    Object.defineProperty(Writable, Symbol.hasInstance, {
      value: function (object) {
        if (realHasInstance.call(this, object)) return true;
        if (this !== Writable) return false;
  
        return object && object._writableState instanceof WritableState;
      }
    });
  } else {
    realHasInstance = function (object) {
      return object instanceof this;
    };
  }
  
  function Writable(options) {
    Duplex = Duplex || require('./_stream_duplex');
  
    // Writable ctor is applied to Duplexes, too.
    // `realHasInstance` is necessary because using plain `instanceof`
    // would return false, as no `_writableState` property is attached.
  
    // Trying to use the custom `instanceof` for Writable here will also break the
    // Node.js LazyTransform implementation, which has a non-trivial getter for
    // `_writableState` that would lead to infinite recursion.
    if (!realHasInstance.call(Writable, this) && !(this instanceof Duplex)) {
      return new Writable(options);
    }
  
    this._writableState = new WritableState(options, this);
  
    // legacy.
    this.writable = true;
  
    if (options) {
      if (typeof options.write === 'function') this._write = options.write;
  
      if (typeof options.writev === 'function') this._writev = options.writev;
  
      if (typeof options.destroy === 'function') this._destroy = options.destroy;
  
      if (typeof options.final === 'function') this._final = options.final;
    }
  
    Stream.call(this);
  }
  
  // Otherwise people can pipe Writable streams, which is just wrong.
  Writable.prototype.pipe = function () {
    this.emit('error', new Error('Cannot pipe, not readable'));
  };
  
  function writeAfterEnd(stream, cb) {
    var er = new Error('write after end');
    // TODO: defer error events consistently everywhere, not just the cb
    stream.emit('error', er);
    pna.nextTick(cb, er);
  }
  
  // Checks that a user-supplied chunk is valid, especially for the particular
  // mode the stream is in. Currently this means that `null` is never accepted
  // and undefined/non-string values are only allowed in object mode.
  function validChunk(stream, state, chunk, cb) {
    var valid = true;
    var er = false;
  
    if (chunk === null) {
      er = new TypeError('May not write null values to stream');
    } else if (typeof chunk !== 'string' && chunk !== undefined && !state.objectMode) {
      er = new TypeError('Invalid non-string/buffer chunk');
    }
    if (er) {
      stream.emit('error', er);
      pna.nextTick(cb, er);
      valid = false;
    }
    return valid;
  }
  
  Writable.prototype.write = function (chunk, encoding, cb) {
    var state = this._writableState;
    var ret = false;
    var isBuf = !state.objectMode && _isUint8Array(chunk);
  
    if (isBuf && !Buffer.isBuffer(chunk)) {
      chunk = _uint8ArrayToBuffer(chunk);
    }
  
    if (typeof encoding === 'function') {
      cb = encoding;
      encoding = null;
    }
  
    if (isBuf) encoding = 'buffer';else if (!encoding) encoding = state.defaultEncoding;
  
    if (typeof cb !== 'function') cb = nop;
  
    if (state.ended) writeAfterEnd(this, cb);else if (isBuf || validChunk(this, state, chunk, cb)) {
      state.pendingcb++;
      ret = writeOrBuffer(this, state, isBuf, chunk, encoding, cb);
    }
  
    return ret;
  };
  
  Writable.prototype.cork = function () {
    var state = this._writableState;
  
    state.corked++;
  };
  
  Writable.prototype.uncork = function () {
    var state = this._writableState;
  
    if (state.corked) {
      state.corked--;
  
      if (!state.writing && !state.corked && !state.finished && !state.bufferProcessing && state.bufferedRequest) clearBuffer(this, state);
    }
  };
  
  Writable.prototype.setDefaultEncoding = function setDefaultEncoding(encoding) {
    // node::ParseEncoding() requires lower case.
    if (typeof encoding === 'string') encoding = encoding.toLowerCase();
    if (!(['hex', 'utf8', 'utf-8', 'ascii', 'binary', 'base64', 'ucs2', 'ucs-2', 'utf16le', 'utf-16le', 'raw'].indexOf((encoding + '').toLowerCase()) > -1)) throw new TypeError('Unknown encoding: ' + encoding);
    this._writableState.defaultEncoding = encoding;
    return this;
  };
  
  function decodeChunk(state, chunk, encoding) {
    if (!state.objectMode && state.decodeStrings !== false && typeof chunk === 'string') {
      chunk = Buffer.from(chunk, encoding);
    }
    return chunk;
  }
  
  Object.defineProperty(Writable.prototype, 'writableHighWaterMark', {
    // making it explicit this property is not enumerable
    // because otherwise some prototype manipulation in
    // userland will fail
    enumerable: false,
    get: function () {
      return this._writableState.highWaterMark;
    }
  });
  
  // if we're already writing something, then just put this
  // in the queue, and wait our turn.  Otherwise, call _write
  // If we return false, then we need a drain event, so set that flag.
  function writeOrBuffer(stream, state, isBuf, chunk, encoding, cb) {
    if (!isBuf) {
      var newChunk = decodeChunk(state, chunk, encoding);
      if (chunk !== newChunk) {
        isBuf = true;
        encoding = 'buffer';
        chunk = newChunk;
      }
    }
    var len = state.objectMode ? 1 : chunk.length;
  
    state.length += len;
  
    var ret = state.length < state.highWaterMark;
    // we must ensure that previous needDrain will not be reset to false.
    if (!ret) state.needDrain = true;
  
    if (state.writing || state.corked) {
      var last = state.lastBufferedRequest;
      state.lastBufferedRequest = {
        chunk: chunk,
        encoding: encoding,
        isBuf: isBuf,
        callback: cb,
        next: null
      };
      if (last) {
        last.next = state.lastBufferedRequest;
      } else {
        state.bufferedRequest = state.lastBufferedRequest;
      }
      state.bufferedRequestCount += 1;
    } else {
      doWrite(stream, state, false, len, chunk, encoding, cb);
    }
  
    return ret;
  }
  
  function doWrite(stream, state, writev, len, chunk, encoding, cb) {
    state.writelen = len;
    state.writecb = cb;
    state.writing = true;
    state.sync = true;
    if (writev) stream._writev(chunk, state.onwrite);else stream._write(chunk, encoding, state.onwrite);
    state.sync = false;
  }
  
  function onwriteError(stream, state, sync, er, cb) {
    --state.pendingcb;
  
    if (sync) {
      // defer the callback if we are being called synchronously
      // to avoid piling up things on the stack
      pna.nextTick(cb, er);
      // this can emit finish, and it will always happen
      // after error
      pna.nextTick(finishMaybe, stream, state);
      stream._writableState.errorEmitted = true;
      stream.emit('error', er);
    } else {
      // the caller expect this to happen before if
      // it is async
      cb(er);
      stream._writableState.errorEmitted = true;
      stream.emit('error', er);
      // this can emit finish, but finish must
      // always follow error
      finishMaybe(stream, state);
    }
  }
  
  function onwriteStateUpdate(state) {
    state.writing = false;
    state.writecb = null;
    state.length -= state.writelen;
    state.writelen = 0;
  }
  
  function onwrite(stream, er) {
    var state = stream._writableState;
    var sync = state.sync;
    var cb = state.writecb;
  
    onwriteStateUpdate(state);
  
    if (er) onwriteError(stream, state, sync, er, cb);else {
      // Check if we're actually ready to finish, but don't emit yet
      var finished = needFinish(state);
  
      if (!finished && !state.corked && !state.bufferProcessing && state.bufferedRequest) {
        clearBuffer(stream, state);
      }
  
      if (sync) {
        /*<replacement>*/
        asyncWrite(afterWrite, stream, state, finished, cb);
        /*</replacement>*/
      } else {
        afterWrite(stream, state, finished, cb);
      }
    }
  }
  
  function afterWrite(stream, state, finished, cb) {
    if (!finished) onwriteDrain(stream, state);
    state.pendingcb--;
    cb();
    finishMaybe(stream, state);
  }
  
  // Must force callback to be called on nextTick, so that we don't
  // emit 'drain' before the write() consumer gets the 'false' return
  // value, and has a chance to attach a 'drain' listener.
  function onwriteDrain(stream, state) {
    if (state.length === 0 && state.needDrain) {
      state.needDrain = false;
      stream.emit('drain');
    }
  }
  
  // if there's something in the buffer waiting, then process it
  function clearBuffer(stream, state) {
    state.bufferProcessing = true;
    var entry = state.bufferedRequest;
  
    if (stream._writev && entry && entry.next) {
      // Fast case, write everything using _writev()
      var l = state.bufferedRequestCount;
      var buffer = new Array(l);
      var holder = state.corkedRequestsFree;
      holder.entry = entry;
  
      var count = 0;
      var allBuffers = true;
      while (entry) {
        buffer[count] = entry;
        if (!entry.isBuf) allBuffers = false;
        entry = entry.next;
        count += 1;
      }
      buffer.allBuffers = allBuffers;
  
      doWrite(stream, state, true, state.length, buffer, '', holder.finish);
  
      // doWrite is almost always async, defer these to save a bit of time
      // as the hot path ends with doWrite
      state.pendingcb++;
      state.lastBufferedRequest = null;
      if (holder.next) {
        state.corkedRequestsFree = holder.next;
        holder.next = null;
      } else {
        state.corkedRequestsFree = new CorkedRequest(state);
      }
      state.bufferedRequestCount = 0;
    } else {
      // Slow case, write chunks one-by-one
      while (entry) {
        var chunk = entry.chunk;
        var encoding = entry.encoding;
        var cb = entry.callback;
        var len = state.objectMode ? 1 : chunk.length;
  
        doWrite(stream, state, false, len, chunk, encoding, cb);
        entry = entry.next;
        state.bufferedRequestCount--;
        // if we didn't call the onwrite immediately, then
        // it means that we need to wait until it does.
        // also, that means that the chunk and cb are currently
        // being processed, so move the buffer counter past them.
        if (state.writing) {
          break;
        }
      }
  
      if (entry === null) state.lastBufferedRequest = null;
    }
  
    state.bufferedRequest = entry;
    state.bufferProcessing = false;
  }
  
  Writable.prototype._write = function (chunk, encoding, cb) {
    cb(new Error('_write() is not implemented'));
  };
  
  Writable.prototype._writev = null;
  
  Writable.prototype.end = function (chunk, encoding, cb) {
    var state = this._writableState;
  
    if (typeof chunk === 'function') {
      cb = chunk;
      chunk = null;
      encoding = null;
    } else if (typeof encoding === 'function') {
      cb = encoding;
      encoding = null;
    }
  
    if (chunk !== null && chunk !== undefined) this.write(chunk, encoding);
  
    // .end() fully uncorks
    if (state.corked) {
      state.corked = 1;
      this.uncork();
    }
  
    // ignore unnecessary end() calls.
    if (!state.ending && !state.finished) endWritable(this, state, cb);
  };
  
  function needFinish(state) {
    return state.ending && state.length === 0 && state.bufferedRequest === null && !state.finished && !state.writing;
  }
  function callFinal(stream, state) {
    stream._final(function (err) {
      state.pendingcb--;
      if (err) {
        stream.emit('error', err);
      }
      state.prefinished = true;
      stream.emit('prefinish');
      finishMaybe(stream, state);
    });
  }
  function prefinish(stream, state) {
    if (!state.prefinished && !state.finalCalled) {
      if (typeof stream._final === 'function') {
        state.pendingcb++;
        state.finalCalled = true;
        pna.nextTick(callFinal, stream, state);
      } else {
        state.prefinished = true;
        stream.emit('prefinish');
      }
    }
  }
  
  function finishMaybe(stream, state) {
    var need = needFinish(state);
    if (need) {
      prefinish(stream, state);
      if (state.pendingcb === 0) {
        state.finished = true;
        stream.emit('finish');
      }
    }
    return need;
  }
  
  function endWritable(stream, state, cb) {
    state.ending = true;
    finishMaybe(stream, state);
    if (cb) {
      if (state.finished) pna.nextTick(cb);else stream.once('finish', cb);
    }
    state.ended = true;
    stream.writable = false;
  }
  
  function onCorkedFinish(corkReq, state, err) {
    var entry = corkReq.entry;
    corkReq.entry = null;
    while (entry) {
      var cb = entry.callback;
      state.pendingcb--;
      cb(err);
      entry = entry.next;
    }
    if (state.corkedRequestsFree) {
      state.corkedRequestsFree.next = corkReq;
    } else {
      state.corkedRequestsFree = corkReq;
    }
  }
  
  Object.defineProperty(Writable.prototype, 'destroyed', {
    get: function () {
      if (this._writableState === undefined) {
        return false;
      }
      return this._writableState.destroyed;
    },
    set: function (value) {
      // we ignore the value if the stream
      // has not been initialized yet
      if (!this._writableState) {
        return;
      }
  
      // backward compatibility, the user is explicitly
      // managing destroyed
      this._writableState.destroyed = value;
    }
  });
  
  Writable.prototype.destroy = destroyImpl.destroy;
  Writable.prototype._undestroy = destroyImpl.undestroy;
  Writable.prototype._destroy = function (err, cb) {
    this.end();
    cb(err);
  };
  }).call(this,require('_process'),typeof global !== "undefined" ? global : typeof self !== "undefined" ? self : typeof window !== "undefined" ? window : {},require("timers").setImmediate)
  },{"./_stream_duplex":17,"./internal/streams/destroy":23,"./internal/streams/stream":24,"_process":44,"core-util-is":13,"inherits":29,"process-nextick-args":43,"safe-buffer":61,"timers":64,"util-deprecate":65}],22:[function(require,module,exports){
  'use strict';
  
  function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
  
  var Buffer = require('safe-buffer').Buffer;
  var util = require('util');
  
  function copyBuffer(src, target, offset) {
    src.copy(target, offset);
  }
  
  module.exports = function () {
    function BufferList() {
      _classCallCheck(this, BufferList);
  
      this.head = null;
      this.tail = null;
      this.length = 0;
    }
  
    BufferList.prototype.push = function push(v) {
      var entry = { data: v, next: null };
      if (this.length > 0) this.tail.next = entry;else this.head = entry;
      this.tail = entry;
      ++this.length;
    };
  
    BufferList.prototype.unshift = function unshift(v) {
      var entry = { data: v, next: this.head };
      if (this.length === 0) this.tail = entry;
      this.head = entry;
      ++this.length;
    };
  
    BufferList.prototype.shift = function shift() {
      if (this.length === 0) return;
      var ret = this.head.data;
      if (this.length === 1) this.head = this.tail = null;else this.head = this.head.next;
      --this.length;
      return ret;
    };
  
    BufferList.prototype.clear = function clear() {
      this.head = this.tail = null;
      this.length = 0;
    };
  
    BufferList.prototype.join = function join(s) {
      if (this.length === 0) return '';
      var p = this.head;
      var ret = '' + p.data;
      while (p = p.next) {
        ret += s + p.data;
      }return ret;
    };
  
    BufferList.prototype.concat = function concat(n) {
      if (this.length === 0) return Buffer.alloc(0);
      if (this.length === 1) return this.head.data;
      var ret = Buffer.allocUnsafe(n >>> 0);
      var p = this.head;
      var i = 0;
      while (p) {
        copyBuffer(p.data, ret, i);
        i += p.data.length;
        p = p.next;
      }
      return ret;
    };
  
    return BufferList;
  }();
  
  if (util && util.inspect && util.inspect.custom) {
    module.exports.prototype[util.inspect.custom] = function () {
      var obj = util.inspect({ length: this.length });
      return this.constructor.name + ' ' + obj;
    };
  }
  },{"safe-buffer":61,"util":11}],23:[function(require,module,exports){
  'use strict';
  
  /*<replacement>*/
  
  var pna = require('process-nextick-args');
  /*</replacement>*/
  
  // undocumented cb() API, needed for core, not for public API
  function destroy(err, cb) {
    var _this = this;
  
    var readableDestroyed = this._readableState && this._readableState.destroyed;
    var writableDestroyed = this._writableState && this._writableState.destroyed;
  
    if (readableDestroyed || writableDestroyed) {
      if (cb) {
        cb(err);
      } else if (err && (!this._writableState || !this._writableState.errorEmitted)) {
        pna.nextTick(emitErrorNT, this, err);
      }
      return this;
    }
  
    // we set destroyed to true before firing error callbacks in order
    // to make it re-entrance safe in case destroy() is called within callbacks
  
    if (this._readableState) {
      this._readableState.destroyed = true;
    }
  
    // if this is a duplex stream mark the writable part as destroyed as well
    if (this._writableState) {
      this._writableState.destroyed = true;
    }
  
    this._destroy(err || null, function (err) {
      if (!cb && err) {
        pna.nextTick(emitErrorNT, _this, err);
        if (_this._writableState) {
          _this._writableState.errorEmitted = true;
        }
      } else if (cb) {
        cb(err);
      }
    });
  
    return this;
  }
  
  function undestroy() {
    if (this._readableState) {
      this._readableState.destroyed = false;
      this._readableState.reading = false;
      this._readableState.ended = false;
      this._readableState.endEmitted = false;
    }
  
    if (this._writableState) {
      this._writableState.destroyed = false;
      this._writableState.ended = false;
      this._writableState.ending = false;
      this._writableState.finished = false;
      this._writableState.errorEmitted = false;
    }
  }
  
  function emitErrorNT(self, err) {
    self.emit('error', err);
  }
  
  module.exports = {
    destroy: destroy,
    undestroy: undestroy
  };
  },{"process-nextick-args":43}],24:[function(require,module,exports){
  module.exports = require('events').EventEmitter;
  
  },{"events":27}],25:[function(require,module,exports){
  exports = module.exports = require('./lib/_stream_readable.js');
  exports.Stream = exports;
  exports.Readable = exports;
  exports.Writable = require('./lib/_stream_writable.js');
  exports.Duplex = require('./lib/_stream_duplex.js');
  exports.Transform = require('./lib/_stream_transform.js');
  exports.PassThrough = require('./lib/_stream_passthrough.js');
  
  },{"./lib/_stream_duplex.js":17,"./lib/_stream_passthrough.js":18,"./lib/_stream_readable.js":19,"./lib/_stream_transform.js":20,"./lib/_stream_writable.js":21}],26:[function(require,module,exports){
  (function (process){
  var once = require('once');
  
  var noop = function() {};
  
  var isRequest = function(stream) {
  	return stream.setHeader && typeof stream.abort === 'function';
  };
  
  var isChildProcess = function(stream) {
  	return stream.stdio && Array.isArray(stream.stdio) && stream.stdio.length === 3
  };
  
  var eos = function(stream, opts, callback) {
  	if (typeof opts === 'function') return eos(stream, null, opts);
  	if (!opts) opts = {};
  
  	callback = once(callback || noop);
  
  	var ws = stream._writableState;
  	var rs = stream._readableState;
  	var readable = opts.readable || (opts.readable !== false && stream.readable);
  	var writable = opts.writable || (opts.writable !== false && stream.writable);
  	var cancelled = false;
  
  	var onlegacyfinish = function() {
  		if (!stream.writable) onfinish();
  	};
  
  	var onfinish = function() {
  		writable = false;
  		if (!readable) callback.call(stream);
  	};
  
  	var onend = function() {
  		readable = false;
  		if (!writable) callback.call(stream);
  	};
  
  	var onexit = function(exitCode) {
  		callback.call(stream, exitCode ? new Error('exited with error code: ' + exitCode) : null);
  	};
  
  	var onerror = function(err) {
  		callback.call(stream, err);
  	};
  
  	var onclose = function() {
  		process.nextTick(onclosenexttick);
  	};
  
  	var onclosenexttick = function() {
  		if (cancelled) return;
  		if (readable && !(rs && (rs.ended && !rs.destroyed))) return callback.call(stream, new Error('premature close'));
  		if (writable && !(ws && (ws.ended && !ws.destroyed))) return callback.call(stream, new Error('premature close'));
  	};
  
  	var onrequest = function() {
  		stream.req.on('finish', onfinish);
  	};
  
  	if (isRequest(stream)) {
  		stream.on('complete', onfinish);
  		stream.on('abort', onclose);
  		if (stream.req) onrequest();
  		else stream.on('request', onrequest);
  	} else if (writable && !ws) { // legacy streams
  		stream.on('end', onlegacyfinish);
  		stream.on('close', onlegacyfinish);
  	}
  
  	if (isChildProcess(stream)) stream.on('exit', onexit);
  
  	stream.on('end', onend);
  	stream.on('finish', onfinish);
  	if (opts.error !== false) stream.on('error', onerror);
  	stream.on('close', onclose);
  
  	return function() {
  		cancelled = true;
  		stream.removeListener('complete', onfinish);
  		stream.removeListener('abort', onclose);
  		stream.removeListener('request', onrequest);
  		if (stream.req) stream.req.removeListener('finish', onfinish);
  		stream.removeListener('end', onlegacyfinish);
  		stream.removeListener('close', onlegacyfinish);
  		stream.removeListener('finish', onfinish);
  		stream.removeListener('exit', onexit);
  		stream.removeListener('end', onend);
  		stream.removeListener('error', onerror);
  		stream.removeListener('close', onclose);
  	};
  };
  
  module.exports = eos;
  
  }).call(this,require('_process'))
  },{"_process":44,"once":42}],27:[function(require,module,exports){
  // Copyright Joyent, Inc. and other Node contributors.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a
  // copy of this software and associated documentation files (the
  // "Software"), to deal in the Software without restriction, including
  // without limitation the rights to use, copy, modify, merge, publish,
  // distribute, sublicense, and/or sell copies of the Software, and to permit
  // persons to whom the Software is furnished to do so, subject to the
  // following conditions:
  //
  // The above copyright notice and this permission notice shall be included
  // in all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
  // NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
  // DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  // USE OR OTHER DEALINGS IN THE SOFTWARE.
  
  var objectCreate = Object.create || objectCreatePolyfill
  var objectKeys = Object.keys || objectKeysPolyfill
  var bind = Function.prototype.bind || functionBindPolyfill
  
  function EventEmitter() {
    if (!this._events || !Object.prototype.hasOwnProperty.call(this, '_events')) {
      this._events = objectCreate(null);
      this._eventsCount = 0;
    }
  
    this._maxListeners = this._maxListeners || undefined;
  }
  module.exports = EventEmitter;
  
  // Backwards-compat with node 0.10.x
  EventEmitter.EventEmitter = EventEmitter;
  
  EventEmitter.prototype._events = undefined;
  EventEmitter.prototype._maxListeners = undefined;
  
  // By default EventEmitters will print a warning if more than 10 listeners are
  // added to it. This is a useful default which helps finding memory leaks.
  var defaultMaxListeners = 10;
  
  var hasDefineProperty;
  try {
    var o = {};
    if (Object.defineProperty) Object.defineProperty(o, 'x', { value: 0 });
    hasDefineProperty = o.x === 0;
  } catch (err) { hasDefineProperty = false }
  if (hasDefineProperty) {
    Object.defineProperty(EventEmitter, 'defaultMaxListeners', {
      enumerable: true,
      get: function() {
        return defaultMaxListeners;
      },
      set: function(arg) {
        // check whether the input is a positive number (whose value is zero or
        // greater and not a NaN).
        if (typeof arg !== 'number' || arg < 0 || arg !== arg)
          throw new TypeError('"defaultMaxListeners" must be a positive number');
        defaultMaxListeners = arg;
      }
    });
  } else {
    EventEmitter.defaultMaxListeners = defaultMaxListeners;
  }
  
  // Obviously not all Emitters should be limited to 10. This function allows
  // that to be increased. Set to zero for unlimited.
  EventEmitter.prototype.setMaxListeners = function setMaxListeners(n) {
    if (typeof n !== 'number' || n < 0 || isNaN(n))
      throw new TypeError('"n" argument must be a positive number');
    this._maxListeners = n;
    return this;
  };
  
  function $getMaxListeners(that) {
    if (that._maxListeners === undefined)
      return EventEmitter.defaultMaxListeners;
    return that._maxListeners;
  }
  
  EventEmitter.prototype.getMaxListeners = function getMaxListeners() {
    return $getMaxListeners(this);
  };
  
  // These standalone emit* functions are used to optimize calling of event
  // handlers for fast cases because emit() itself often has a variable number of
  // arguments and can be deoptimized because of that. These functions always have
  // the same number of arguments and thus do not get deoptimized, so the code
  // inside them can execute faster.
  function emitNone(handler, isFn, self) {
    if (isFn)
      handler.call(self);
    else {
      var len = handler.length;
      var listeners = arrayClone(handler, len);
      for (var i = 0; i < len; ++i)
        listeners[i].call(self);
    }
  }
  function emitOne(handler, isFn, self, arg1) {
    if (isFn)
      handler.call(self, arg1);
    else {
      var len = handler.length;
      var listeners = arrayClone(handler, len);
      for (var i = 0; i < len; ++i)
        listeners[i].call(self, arg1);
    }
  }
  function emitTwo(handler, isFn, self, arg1, arg2) {
    if (isFn)
      handler.call(self, arg1, arg2);
    else {
      var len = handler.length;
      var listeners = arrayClone(handler, len);
      for (var i = 0; i < len; ++i)
        listeners[i].call(self, arg1, arg2);
    }
  }
  function emitThree(handler, isFn, self, arg1, arg2, arg3) {
    if (isFn)
      handler.call(self, arg1, arg2, arg3);
    else {
      var len = handler.length;
      var listeners = arrayClone(handler, len);
      for (var i = 0; i < len; ++i)
        listeners[i].call(self, arg1, arg2, arg3);
    }
  }
  
  function emitMany(handler, isFn, self, args) {
    if (isFn)
      handler.apply(self, args);
    else {
      var len = handler.length;
      var listeners = arrayClone(handler, len);
      for (var i = 0; i < len; ++i)
        listeners[i].apply(self, args);
    }
  }
  
  EventEmitter.prototype.emit = function emit(type) {
    var er, handler, len, args, i, events;
    var doError = (type === 'error');
  
    events = this._events;
    if (events)
      doError = (doError && events.error == null);
    else if (!doError)
      return false;
  
    // If there is no 'error' event listener then throw.
    if (doError) {
      if (arguments.length > 1)
        er = arguments[1];
      if (er instanceof Error) {
        throw er; // Unhandled 'error' event
      } else {
        // At least give some kind of context to the user
        var err = new Error('Unhandled "error" event. (' + er + ')');
        err.context = er;
        throw err;
      }
      return false;
    }
  
    handler = events[type];
  
    if (!handler)
      return false;
  
    var isFn = typeof handler === 'function';
    len = arguments.length;
    switch (len) {
        // fast cases
      case 1:
        emitNone(handler, isFn, this);
        break;
      case 2:
        emitOne(handler, isFn, this, arguments[1]);
        break;
      case 3:
        emitTwo(handler, isFn, this, arguments[1], arguments[2]);
        break;
      case 4:
        emitThree(handler, isFn, this, arguments[1], arguments[2], arguments[3]);
        break;
        // slower
      default:
        args = new Array(len - 1);
        for (i = 1; i < len; i++)
          args[i - 1] = arguments[i];
        emitMany(handler, isFn, this, args);
    }
  
    return true;
  };
  
  function _addListener(target, type, listener, prepend) {
    var m;
    var events;
    var existing;
  
    if (typeof listener !== 'function')
      throw new TypeError('"listener" argument must be a function');
  
    events = target._events;
    if (!events) {
      events = target._events = objectCreate(null);
      target._eventsCount = 0;
    } else {
      // To avoid recursion in the case that type === "newListener"! Before
      // adding it to the listeners, first emit "newListener".
      if (events.newListener) {
        target.emit('newListener', type,
            listener.listener ? listener.listener : listener);
  
        // Re-assign `events` because a newListener handler could have caused the
        // this._events to be assigned to a new object
        events = target._events;
      }
      existing = events[type];
    }
  
    if (!existing) {
      // Optimize the case of one listener. Don't need the extra array object.
      existing = events[type] = listener;
      ++target._eventsCount;
    } else {
      if (typeof existing === 'function') {
        // Adding the second element, need to change to array.
        existing = events[type] =
            prepend ? [listener, existing] : [existing, listener];
      } else {
        // If we've already got an array, just append.
        if (prepend) {
          existing.unshift(listener);
        } else {
          existing.push(listener);
        }
      }
  
      // Check for listener leak
      if (!existing.warned) {
        m = $getMaxListeners(target);
        if (m && m > 0 && existing.length > m) {
          existing.warned = true;
          var w = new Error('Possible EventEmitter memory leak detected. ' +
              existing.length + ' "' + String(type) + '" listeners ' +
              'added. Use emitter.setMaxListeners() to ' +
              'increase limit.');
          w.name = 'MaxListenersExceededWarning';
          w.emitter = target;
          w.type = type;
          w.count = existing.length;
          if (typeof console === 'object' && console.warn) {
            console.warn('%s: %s', w.name, w.message);
          }
        }
      }
    }
  
    return target;
  }
  
  EventEmitter.prototype.addListener = function addListener(type, listener) {
    return _addListener(this, type, listener, false);
  };
  
  EventEmitter.prototype.on = EventEmitter.prototype.addListener;
  
  EventEmitter.prototype.prependListener =
      function prependListener(type, listener) {
        return _addListener(this, type, listener, true);
      };
  
  function onceWrapper() {
    if (!this.fired) {
      this.target.removeListener(this.type, this.wrapFn);
      this.fired = true;
      switch (arguments.length) {
        case 0:
          return this.listener.call(this.target);
        case 1:
          return this.listener.call(this.target, arguments[0]);
        case 2:
          return this.listener.call(this.target, arguments[0], arguments[1]);
        case 3:
          return this.listener.call(this.target, arguments[0], arguments[1],
              arguments[2]);
        default:
          var args = new Array(arguments.length);
          for (var i = 0; i < args.length; ++i)
            args[i] = arguments[i];
          this.listener.apply(this.target, args);
      }
    }
  }
  
  function _onceWrap(target, type, listener) {
    var state = { fired: false, wrapFn: undefined, target: target, type: type, listener: listener };
    var wrapped = bind.call(onceWrapper, state);
    wrapped.listener = listener;
    state.wrapFn = wrapped;
    return wrapped;
  }
  
  EventEmitter.prototype.once = function once(type, listener) {
    if (typeof listener !== 'function')
      throw new TypeError('"listener" argument must be a function');
    this.on(type, _onceWrap(this, type, listener));
    return this;
  };
  
  EventEmitter.prototype.prependOnceListener =
      function prependOnceListener(type, listener) {
        if (typeof listener !== 'function')
          throw new TypeError('"listener" argument must be a function');
        this.prependListener(type, _onceWrap(this, type, listener));
        return this;
      };
  
  // Emits a 'removeListener' event if and only if the listener was removed.
  EventEmitter.prototype.removeListener =
      function removeListener(type, listener) {
        var list, events, position, i, originalListener;
  
        if (typeof listener !== 'function')
          throw new TypeError('"listener" argument must be a function');
  
        events = this._events;
        if (!events)
          return this;
  
        list = events[type];
        if (!list)
          return this;
  
        if (list === listener || list.listener === listener) {
          if (--this._eventsCount === 0)
            this._events = objectCreate(null);
          else {
            delete events[type];
            if (events.removeListener)
              this.emit('removeListener', type, list.listener || listener);
          }
        } else if (typeof list !== 'function') {
          position = -1;
  
          for (i = list.length - 1; i >= 0; i--) {
            if (list[i] === listener || list[i].listener === listener) {
              originalListener = list[i].listener;
              position = i;
              break;
            }
          }
  
          if (position < 0)
            return this;
  
          if (position === 0)
            list.shift();
          else
            spliceOne(list, position);
  
          if (list.length === 1)
            events[type] = list[0];
  
          if (events.removeListener)
            this.emit('removeListener', type, originalListener || listener);
        }
  
        return this;
      };
  
  EventEmitter.prototype.removeAllListeners =
      function removeAllListeners(type) {
        var listeners, events, i;
  
        events = this._events;
        if (!events)
          return this;
  
        // not listening for removeListener, no need to emit
        if (!events.removeListener) {
          if (arguments.length === 0) {
            this._events = objectCreate(null);
            this._eventsCount = 0;
          } else if (events[type]) {
            if (--this._eventsCount === 0)
              this._events = objectCreate(null);
            else
              delete events[type];
          }
          return this;
        }
  
        // emit removeListener for all listeners on all events
        if (arguments.length === 0) {
          var keys = objectKeys(events);
          var key;
          for (i = 0; i < keys.length; ++i) {
            key = keys[i];
            if (key === 'removeListener') continue;
            this.removeAllListeners(key);
          }
          this.removeAllListeners('removeListener');
          this._events = objectCreate(null);
          this._eventsCount = 0;
          return this;
        }
  
        listeners = events[type];
  
        if (typeof listeners === 'function') {
          this.removeListener(type, listeners);
        } else if (listeners) {
          // LIFO order
          for (i = listeners.length - 1; i >= 0; i--) {
            this.removeListener(type, listeners[i]);
          }
        }
  
        return this;
      };
  
  function _listeners(target, type, unwrap) {
    var events = target._events;
  
    if (!events)
      return [];
  
    var evlistener = events[type];
    if (!evlistener)
      return [];
  
    if (typeof evlistener === 'function')
      return unwrap ? [evlistener.listener || evlistener] : [evlistener];
  
    return unwrap ? unwrapListeners(evlistener) : arrayClone(evlistener, evlistener.length);
  }
  
  EventEmitter.prototype.listeners = function listeners(type) {
    return _listeners(this, type, true);
  };
  
  EventEmitter.prototype.rawListeners = function rawListeners(type) {
    return _listeners(this, type, false);
  };
  
  EventEmitter.listenerCount = function(emitter, type) {
    if (typeof emitter.listenerCount === 'function') {
      return emitter.listenerCount(type);
    } else {
      return listenerCount.call(emitter, type);
    }
  };
  
  EventEmitter.prototype.listenerCount = listenerCount;
  function listenerCount(type) {
    var events = this._events;
  
    if (events) {
      var evlistener = events[type];
  
      if (typeof evlistener === 'function') {
        return 1;
      } else if (evlistener) {
        return evlistener.length;
      }
    }
  
    return 0;
  }
  
  EventEmitter.prototype.eventNames = function eventNames() {
    return this._eventsCount > 0 ? Reflect.ownKeys(this._events) : [];
  };
  
  // About 1.5x faster than the two-arg version of Array#splice().
  function spliceOne(list, index) {
    for (var i = index, k = i + 1, n = list.length; k < n; i += 1, k += 1)
      list[i] = list[k];
    list.pop();
  }
  
  function arrayClone(arr, n) {
    var copy = new Array(n);
    for (var i = 0; i < n; ++i)
      copy[i] = arr[i];
    return copy;
  }
  
  function unwrapListeners(arr) {
    var ret = new Array(arr.length);
    for (var i = 0; i < ret.length; ++i) {
      ret[i] = arr[i].listener || arr[i];
    }
    return ret;
  }
  
  function objectCreatePolyfill(proto) {
    var F = function() {};
    F.prototype = proto;
    return new F;
  }
  function objectKeysPolyfill(obj) {
    var keys = [];
    for (var k in obj) if (Object.prototype.hasOwnProperty.call(obj, k)) {
      keys.push(k);
    }
    return k;
  }
  function functionBindPolyfill(context) {
    var fn = this;
    return function () {
      return fn.apply(context, arguments);
    };
  }
  
  },{}],28:[function(require,module,exports){
  exports.read = function (buffer, offset, isLE, mLen, nBytes) {
    var e, m
    var eLen = (nBytes * 8) - mLen - 1
    var eMax = (1 << eLen) - 1
    var eBias = eMax >> 1
    var nBits = -7
    var i = isLE ? (nBytes - 1) : 0
    var d = isLE ? -1 : 1
    var s = buffer[offset + i]
  
    i += d
  
    e = s & ((1 << (-nBits)) - 1)
    s >>= (-nBits)
    nBits += eLen
    for (; nBits > 0; e = (e * 256) + buffer[offset + i], i += d, nBits -= 8) {}
  
    m = e & ((1 << (-nBits)) - 1)
    e >>= (-nBits)
    nBits += mLen
    for (; nBits > 0; m = (m * 256) + buffer[offset + i], i += d, nBits -= 8) {}
  
    if (e === 0) {
      e = 1 - eBias
    } else if (e === eMax) {
      return m ? NaN : ((s ? -1 : 1) * Infinity)
    } else {
      m = m + Math.pow(2, mLen)
      e = e - eBias
    }
    return (s ? -1 : 1) * m * Math.pow(2, e - mLen)
  }
  
  exports.write = function (buffer, value, offset, isLE, mLen, nBytes) {
    var e, m, c
    var eLen = (nBytes * 8) - mLen - 1
    var eMax = (1 << eLen) - 1
    var eBias = eMax >> 1
    var rt = (mLen === 23 ? Math.pow(2, -24) - Math.pow(2, -77) : 0)
    var i = isLE ? 0 : (nBytes - 1)
    var d = isLE ? 1 : -1
    var s = value < 0 || (value === 0 && 1 / value < 0) ? 1 : 0
  
    value = Math.abs(value)
  
    if (isNaN(value) || value === Infinity) {
      m = isNaN(value) ? 1 : 0
      e = eMax
    } else {
      e = Math.floor(Math.log(value) / Math.LN2)
      if (value * (c = Math.pow(2, -e)) < 1) {
        e--
        c *= 2
      }
      if (e + eBias >= 1) {
        value += rt / c
      } else {
        value += rt * Math.pow(2, 1 - eBias)
      }
      if (value * c >= 2) {
        e++
        c /= 2
      }
  
      if (e + eBias >= eMax) {
        m = 0
        e = eMax
      } else if (e + eBias >= 1) {
        m = ((value * c) - 1) * Math.pow(2, mLen)
        e = e + eBias
      } else {
        m = value * Math.pow(2, eBias - 1) * Math.pow(2, mLen)
        e = 0
      }
    }
  
    for (; mLen >= 8; buffer[offset + i] = m & 0xff, i += d, m /= 256, mLen -= 8) {}
  
    e = (e << mLen) | m
    eLen += mLen
    for (; eLen > 0; buffer[offset + i] = e & 0xff, i += d, e /= 256, eLen -= 8) {}
  
    buffer[offset + i - d] |= s * 128
  }
  
  },{}],29:[function(require,module,exports){
  if (typeof Object.create === 'function') {
    // implementation from standard node.js 'util' module
    module.exports = function inherits(ctor, superCtor) {
      if (superCtor) {
        ctor.super_ = superCtor
        ctor.prototype = Object.create(superCtor.prototype, {
          constructor: {
            value: ctor,
            enumerable: false,
            writable: true,
            configurable: true
          }
        })
      }
    };
  } else {
    // old school shim for old browsers
    module.exports = function inherits(ctor, superCtor) {
      if (superCtor) {
        ctor.super_ = superCtor
        var TempCtor = function () {}
        TempCtor.prototype = superCtor.prototype
        ctor.prototype = new TempCtor()
        ctor.prototype.constructor = ctor
      }
    }
  }
  
  },{}],30:[function(require,module,exports){
  /*!
   * Determine if an object is a Buffer
   *
   * @author   Feross Aboukhadijeh <https://feross.org>
   * @license  MIT
   */
  
  // The _isBuffer check is for Safari 5-7 support, because it's missing
  // Object.prototype.constructor. Remove this eventually
  module.exports = function (obj) {
    return obj != null && (isBuffer(obj) || isSlowBuffer(obj) || !!obj._isBuffer)
  }
  
  function isBuffer (obj) {
    return !!obj.constructor && typeof obj.constructor.isBuffer === 'function' && obj.constructor.isBuffer(obj)
  }
  
  // For Node v0.10 support. Remove this eventually.
  function isSlowBuffer (obj) {
    return typeof obj.readFloatLE === 'function' && typeof obj.slice === 'function' && isBuffer(obj.slice(0, 0))
  }
  
  },{}],31:[function(require,module,exports){
  var toString = {}.toString;
  
  module.exports = Array.isArray || function (arr) {
    return toString.call(arr) == '[object Array]';
  };
  
  },{}],32:[function(require,module,exports){
  (function (Buffer){
  /* Protocol - protocol constants */
  const protocol = module.exports
  
  /* Command code => mnemonic */
  protocol.types = {
    0: 'reserved',
    1: 'connect',
    2: 'connack',
    3: 'publish',
    4: 'puback',
    5: 'pubrec',
    6: 'pubrel',
    7: 'pubcomp',
    8: 'subscribe',
    9: 'suback',
    10: 'unsubscribe',
    11: 'unsuback',
    12: 'pingreq',
    13: 'pingresp',
    14: 'disconnect',
    15: 'auth'
  }
  
  /* Mnemonic => Command code */
  protocol.codes = {}
  for (const k in protocol.types) {
    const v = protocol.types[k]
    protocol.codes[v] = k
  }
  
  /* Header */
  protocol.CMD_SHIFT = 4
  protocol.CMD_MASK = 0xF0
  protocol.DUP_MASK = 0x08
  protocol.QOS_MASK = 0x03
  protocol.QOS_SHIFT = 1
  protocol.RETAIN_MASK = 0x01
  
  /* Length */
  protocol.VARBYTEINT_MASK = 0x7F
  protocol.VARBYTEINT_FIN_MASK = 0x80
  
  /* Connack */
  protocol.SESSIONPRESENT_MASK = 0x01
  protocol.SESSIONPRESENT_HEADER = Buffer.from([protocol.SESSIONPRESENT_MASK])
  protocol.CONNACK_HEADER = Buffer.from([protocol.codes.connack << protocol.CMD_SHIFT])
  
  /* Connect */
  protocol.USERNAME_MASK = 0x80
  protocol.PASSWORD_MASK = 0x40
  protocol.WILL_RETAIN_MASK = 0x20
  protocol.WILL_QOS_MASK = 0x18
  protocol.WILL_QOS_SHIFT = 3
  protocol.WILL_FLAG_MASK = 0x04
  protocol.CLEAN_SESSION_MASK = 0x02
  protocol.CONNECT_HEADER = Buffer.from([protocol.codes.connect << protocol.CMD_SHIFT])
  
  /* Properties */
  protocol.properties = {
    sessionExpiryInterval: 17,
    willDelayInterval: 24,
    receiveMaximum: 33,
    maximumPacketSize: 39,
    topicAliasMaximum: 34,
    requestResponseInformation: 25,
    requestProblemInformation: 23,
    userProperties: 38,
    authenticationMethod: 21,
    authenticationData: 22,
    payloadFormatIndicator: 1,
    messageExpiryInterval: 2,
    contentType: 3,
    responseTopic: 8,
    correlationData: 9,
    maximumQoS: 36,
    retainAvailable: 37,
    assignedClientIdentifier: 18,
    reasonString: 31,
    wildcardSubscriptionAvailable: 40,
    subscriptionIdentifiersAvailable: 41,
    sharedSubscriptionAvailable: 42,
    serverKeepAlive: 19,
    responseInformation: 26,
    serverReference: 28,
    topicAlias: 35,
    subscriptionIdentifier: 11
  }
  protocol.propertiesCodes = {}
  for (const prop in protocol.properties) {
    const id = protocol.properties[prop]
    protocol.propertiesCodes[id] = prop
  }
  protocol.propertiesTypes = {
    sessionExpiryInterval: 'int32',
    willDelayInterval: 'int32',
    receiveMaximum: 'int16',
    maximumPacketSize: 'int32',
    topicAliasMaximum: 'int16',
    requestResponseInformation: 'byte',
    requestProblemInformation: 'byte',
    userProperties: 'pair',
    authenticationMethod: 'string',
    authenticationData: 'binary',
    payloadFormatIndicator: 'byte',
    messageExpiryInterval: 'int32',
    contentType: 'string',
    responseTopic: 'string',
    correlationData: 'binary',
    maximumQoS: 'int8',
    retainAvailable: 'byte',
    assignedClientIdentifier: 'string',
    reasonString: 'string',
    wildcardSubscriptionAvailable: 'byte',
    subscriptionIdentifiersAvailable: 'byte',
    sharedSubscriptionAvailable: 'byte',
    serverKeepAlive: 'int16',
    responseInformation: 'string',
    serverReference: 'string',
    topicAlias: 'int16',
    subscriptionIdentifier: 'var'
  }
  
  function genHeader (type) {
    return [0, 1, 2].map(qos => {
      return [0, 1].map(dup => {
        return [0, 1].map(retain => {
          const buf = Buffer.alloc(1)
          buf.writeUInt8(
            protocol.codes[type] << protocol.CMD_SHIFT |
            (dup ? protocol.DUP_MASK : 0) |
            qos << protocol.QOS_SHIFT | retain, 0, true)
          return buf
        })
      })
    })
  }
  
  /* Publish */
  protocol.PUBLISH_HEADER = genHeader('publish')
  
  /* Subscribe */
  protocol.SUBSCRIBE_HEADER = genHeader('subscribe')
  protocol.SUBSCRIBE_OPTIONS_QOS_MASK = 0x03
  protocol.SUBSCRIBE_OPTIONS_NL_MASK = 0x01
  protocol.SUBSCRIBE_OPTIONS_NL_SHIFT = 2
  protocol.SUBSCRIBE_OPTIONS_RAP_MASK = 0x01
  protocol.SUBSCRIBE_OPTIONS_RAP_SHIFT = 3
  protocol.SUBSCRIBE_OPTIONS_RH_MASK = 0x03
  protocol.SUBSCRIBE_OPTIONS_RH_SHIFT = 4
  protocol.SUBSCRIBE_OPTIONS_RH = [0x00, 0x10, 0x20]
  protocol.SUBSCRIBE_OPTIONS_NL = 0x04
  protocol.SUBSCRIBE_OPTIONS_RAP = 0x08
  protocol.SUBSCRIBE_OPTIONS_QOS = [0x00, 0x01, 0x02]
  
  /* Unsubscribe */
  protocol.UNSUBSCRIBE_HEADER = genHeader('unsubscribe')
  
  /* Confirmations */
  protocol.ACKS = {
    unsuback: genHeader('unsuback'),
    puback: genHeader('puback'),
    pubcomp: genHeader('pubcomp'),
    pubrel: genHeader('pubrel'),
    pubrec: genHeader('pubrec')
  }
  
  protocol.SUBACK_HEADER = Buffer.from([protocol.codes.suback << protocol.CMD_SHIFT])
  
  /* Protocol versions */
  protocol.VERSION3 = Buffer.from([3])
  protocol.VERSION4 = Buffer.from([4])
  protocol.VERSION5 = Buffer.from([5])
  
  /* QoS */
  protocol.QOS = [0, 1, 2].map(qos => {
    return Buffer.from([qos])
  })
  
  /* Empty packets */
  protocol.EMPTY = {
    pingreq: Buffer.from([protocol.codes.pingreq << 4, 0]),
    pingresp: Buffer.from([protocol.codes.pingresp << 4, 0]),
    disconnect: Buffer.from([protocol.codes.disconnect << 4, 0])
  }
  
  }).call(this,require("buffer").Buffer)
  },{"buffer":12}],33:[function(require,module,exports){
  (function (Buffer){
  const writeToStream = require('./writeToStream')
  const EventEmitter = require('events')
  
  function generate (packet, opts) {
    const stream = new Accumulator()
    writeToStream(packet, stream, opts)
    return stream.concat()
  }
  
  class Accumulator extends EventEmitter {
    constructor () {
      super()
      this._array = new Array(20)
      this._i = 0
    }
  
    write (chunk) {
      this._array[this._i++] = chunk
      return true
    }
  
    concat () {
      let length = 0
      const lengths = new Array(this._array.length)
      const list = this._array
      let pos = 0
      let i
  
      for (i = 0; i < list.length && list[i] !== undefined; i++) {
        if (typeof list[i] !== 'string') lengths[i] = list[i].length
        else lengths[i] = Buffer.byteLength(list[i])
  
        length += lengths[i]
      }
  
      const result = Buffer.allocUnsafe(length)
  
      for (i = 0; i < list.length && list[i] !== undefined; i++) {
        if (typeof list[i] !== 'string') {
          list[i].copy(result, pos)
          pos += lengths[i]
        } else {
          result.write(list[i], pos)
          pos += lengths[i]
        }
      }
  
      return result
    }
  }
  
  module.exports = generate
  
  }).call(this,require("buffer").Buffer)
  },{"./writeToStream":40,"buffer":12,"events":27}],34:[function(require,module,exports){
  exports.parser = require('./parser').parser
  exports.generate = require('./generate')
  exports.writeToStream = require('./writeToStream')
  
  },{"./generate":33,"./parser":39,"./writeToStream":40}],35:[function(require,module,exports){
  'use strict'
  
  const { Buffer } = require('buffer')
  const symbol = Symbol.for('BufferList')
  
  function BufferList (buf) {
    if (!(this instanceof BufferList)) {
      return new BufferList(buf)
    }
  
    BufferList._init.call(this, buf)
  }
  
  BufferList._init = function _init (buf) {
    Object.defineProperty(this, symbol, { value: true })
  
    this._bufs = []
    this.length = 0
  
    if (buf) {
      this.append(buf)
    }
  }
  
  BufferList.prototype._new = function _new (buf) {
    return new BufferList(buf)
  }
  
  BufferList.prototype._offset = function _offset (offset) {
    if (offset === 0) {
      return [0, 0]
    }
  
    let tot = 0
  
    for (let i = 0; i < this._bufs.length; i++) {
      const _t = tot + this._bufs[i].length
      if (offset < _t || i === this._bufs.length - 1) {
        return [i, offset - tot]
      }
      tot = _t
    }
  }
  
  BufferList.prototype._reverseOffset = function (blOffset) {
    const bufferId = blOffset[0]
    let offset = blOffset[1]
  
    for (let i = 0; i < bufferId; i++) {
      offset += this._bufs[i].length
    }
  
    return offset
  }
  
  BufferList.prototype.get = function get (index) {
    if (index > this.length || index < 0) {
      return undefined
    }
  
    const offset = this._offset(index)
  
    return this._bufs[offset[0]][offset[1]]
  }
  
  BufferList.prototype.slice = function slice (start, end) {
    if (typeof start === 'number' && start < 0) {
      start += this.length
    }
  
    if (typeof end === 'number' && end < 0) {
      end += this.length
    }
  
    return this.copy(null, 0, start, end)
  }
  
  BufferList.prototype.copy = function copy (dst, dstStart, srcStart, srcEnd) {
    if (typeof srcStart !== 'number' || srcStart < 0) {
      srcStart = 0
    }
  
    if (typeof srcEnd !== 'number' || srcEnd > this.length) {
      srcEnd = this.length
    }
  
    if (srcStart >= this.length) {
      return dst || Buffer.alloc(0)
    }
  
    if (srcEnd <= 0) {
      return dst || Buffer.alloc(0)
    }
  
    const copy = !!dst
    const off = this._offset(srcStart)
    const len = srcEnd - srcStart
    let bytes = len
    let bufoff = (copy && dstStart) || 0
    let start = off[1]
  
    // copy/slice everything
    if (srcStart === 0 && srcEnd === this.length) {
      if (!copy) {
        // slice, but full concat if multiple buffers
        return this._bufs.length === 1
          ? this._bufs[0]
          : Buffer.concat(this._bufs, this.length)
      }
  
      // copy, need to copy individual buffers
      for (let i = 0; i < this._bufs.length; i++) {
        this._bufs[i].copy(dst, bufoff)
        bufoff += this._bufs[i].length
      }
  
      return dst
    }
  
    // easy, cheap case where it's a subset of one of the buffers
    if (bytes <= this._bufs[off[0]].length - start) {
      return copy
        ? this._bufs[off[0]].copy(dst, dstStart, start, start + bytes)
        : this._bufs[off[0]].slice(start, start + bytes)
    }
  
    if (!copy) {
      // a slice, we need something to copy in to
      dst = Buffer.allocUnsafe(len)
    }
  
    for (let i = off[0]; i < this._bufs.length; i++) {
      const l = this._bufs[i].length - start
  
      if (bytes > l) {
        this._bufs[i].copy(dst, bufoff, start)
        bufoff += l
      } else {
        this._bufs[i].copy(dst, bufoff, start, start + bytes)
        bufoff += l
        break
      }
  
      bytes -= l
  
      if (start) {
        start = 0
      }
    }
  
    // safeguard so that we don't return uninitialized memory
    if (dst.length > bufoff) return dst.slice(0, bufoff)
  
    return dst
  }
  
  BufferList.prototype.shallowSlice = function shallowSlice (start, end) {
    start = start || 0
    end = typeof end !== 'number' ? this.length : end
  
    if (start < 0) {
      start += this.length
    }
  
    if (end < 0) {
      end += this.length
    }
  
    if (start === end) {
      return this._new()
    }
  
    const startOffset = this._offset(start)
    const endOffset = this._offset(end)
    const buffers = this._bufs.slice(startOffset[0], endOffset[0] + 1)
  
    if (endOffset[1] === 0) {
      buffers.pop()
    } else {
      buffers[buffers.length - 1] = buffers[buffers.length - 1].slice(0, endOffset[1])
    }
  
    if (startOffset[1] !== 0) {
      buffers[0] = buffers[0].slice(startOffset[1])
    }
  
    return this._new(buffers)
  }
  
  BufferList.prototype.toString = function toString (encoding, start, end) {
    return this.slice(start, end).toString(encoding)
  }
  
  BufferList.prototype.consume = function consume (bytes) {
    // first, normalize the argument, in accordance with how Buffer does it
    bytes = Math.trunc(bytes)
    // do nothing if not a positive number
    if (Number.isNaN(bytes) || bytes <= 0) return this
  
    while (this._bufs.length) {
      if (bytes >= this._bufs[0].length) {
        bytes -= this._bufs[0].length
        this.length -= this._bufs[0].length
        this._bufs.shift()
      } else {
        this._bufs[0] = this._bufs[0].slice(bytes)
        this.length -= bytes
        break
      }
    }
  
    return this
  }
  
  BufferList.prototype.duplicate = function duplicate () {
    const copy = this._new()
  
    for (let i = 0; i < this._bufs.length; i++) {
      copy.append(this._bufs[i])
    }
  
    return copy
  }
  
  BufferList.prototype.append = function append (buf) {
    if (buf == null) {
      return this
    }
  
    if (buf.buffer) {
      // append a view of the underlying ArrayBuffer
      this._appendBuffer(Buffer.from(buf.buffer, buf.byteOffset, buf.byteLength))
    } else if (Array.isArray(buf)) {
      for (let i = 0; i < buf.length; i++) {
        this.append(buf[i])
      }
    } else if (this._isBufferList(buf)) {
      // unwrap argument into individual BufferLists
      for (let i = 0; i < buf._bufs.length; i++) {
        this.append(buf._bufs[i])
      }
    } else {
      // coerce number arguments to strings, since Buffer(number) does
      // uninitialized memory allocation
      if (typeof buf === 'number') {
        buf = buf.toString()
      }
  
      this._appendBuffer(Buffer.from(buf))
    }
  
    return this
  }
  
  BufferList.prototype._appendBuffer = function appendBuffer (buf) {
    this._bufs.push(buf)
    this.length += buf.length
  }
  
  BufferList.prototype.indexOf = function (search, offset, encoding) {
    if (encoding === undefined && typeof offset === 'string') {
      encoding = offset
      offset = undefined
    }
  
    if (typeof search === 'function' || Array.isArray(search)) {
      throw new TypeError('The "value" argument must be one of type string, Buffer, BufferList, or Uint8Array.')
    } else if (typeof search === 'number') {
      search = Buffer.from([search])
    } else if (typeof search === 'string') {
      search = Buffer.from(search, encoding)
    } else if (this._isBufferList(search)) {
      search = search.slice()
    } else if (Array.isArray(search.buffer)) {
      search = Buffer.from(search.buffer, search.byteOffset, search.byteLength)
    } else if (!Buffer.isBuffer(search)) {
      search = Buffer.from(search)
    }
  
    offset = Number(offset || 0)
  
    if (isNaN(offset)) {
      offset = 0
    }
  
    if (offset < 0) {
      offset = this.length + offset
    }
  
    if (offset < 0) {
      offset = 0
    }
  
    if (search.length === 0) {
      return offset > this.length ? this.length : offset
    }
  
    const blOffset = this._offset(offset)
    let blIndex = blOffset[0] // index of which internal buffer we're working on
    let buffOffset = blOffset[1] // offset of the internal buffer we're working on
  
    // scan over each buffer
    for (; blIndex < this._bufs.length; blIndex++) {
      const buff = this._bufs[blIndex]
  
      while (buffOffset < buff.length) {
        const availableWindow = buff.length - buffOffset
  
        if (availableWindow >= search.length) {
          const nativeSearchResult = buff.indexOf(search, buffOffset)
  
          if (nativeSearchResult !== -1) {
            return this._reverseOffset([blIndex, nativeSearchResult])
          }
  
          buffOffset = buff.length - search.length + 1 // end of native search window
        } else {
          const revOffset = this._reverseOffset([blIndex, buffOffset])
  
          if (this._match(revOffset, search)) {
            return revOffset
          }
  
          buffOffset++
        }
      }
  
      buffOffset = 0
    }
  
    return -1
  }
  
  BufferList.prototype._match = function (offset, search) {
    if (this.length - offset < search.length) {
      return false
    }
  
    for (let searchOffset = 0; searchOffset < search.length; searchOffset++) {
      if (this.get(offset + searchOffset) !== search[searchOffset]) {
        return false
      }
    }
    return true
  }
  
  ;(function () {
    const methods = {
      readDoubleBE: 8,
      readDoubleLE: 8,
      readFloatBE: 4,
      readFloatLE: 4,
      readInt32BE: 4,
      readInt32LE: 4,
      readUInt32BE: 4,
      readUInt32LE: 4,
      readInt16BE: 2,
      readInt16LE: 2,
      readUInt16BE: 2,
      readUInt16LE: 2,
      readInt8: 1,
      readUInt8: 1,
      readIntBE: null,
      readIntLE: null,
      readUIntBE: null,
      readUIntLE: null
    }
  
    for (const m in methods) {
      (function (m) {
        if (methods[m] === null) {
          BufferList.prototype[m] = function (offset, byteLength) {
            return this.slice(offset, offset + byteLength)[m](0, byteLength)
          }
        } else {
          BufferList.prototype[m] = function (offset) {
            return this.slice(offset, offset + methods[m])[m](0)
          }
        }
      }(m))
    }
  }())
  
  // Used internally by the class and also as an indicator of this object being
  // a `BufferList`. It's not possible to use `instanceof BufferList` in a browser
  // environment because there could be multiple different copies of the
  // BufferList class and some `BufferList`s might be `BufferList`s.
  BufferList.prototype._isBufferList = function _isBufferList (b) {
    return b instanceof BufferList || BufferList.isBufferList(b)
  }
  
  BufferList.isBufferList = function isBufferList (b) {
    return b != null && b[symbol]
  }
  
  module.exports = BufferList
  
  },{"buffer":12}],36:[function(require,module,exports){
  'use strict'
  
  const DuplexStream = require('readable-stream').Duplex
  const inherits = require('inherits')
  const BufferList = require('./BufferList')
  
  function BufferListStream (callback) {
    if (!(this instanceof BufferListStream)) {
      return new BufferListStream(callback)
    }
  
    if (typeof callback === 'function') {
      this._callback = callback
  
      const piper = function piper (err) {
        if (this._callback) {
          this._callback(err)
          this._callback = null
        }
      }.bind(this)
  
      this.on('pipe', function onPipe (src) {
        src.on('error', piper)
      })
      this.on('unpipe', function onUnpipe (src) {
        src.removeListener('error', piper)
      })
  
      callback = null
    }
  
    BufferList._init.call(this, callback)
    DuplexStream.call(this)
  }
  
  inherits(BufferListStream, DuplexStream)
  Object.assign(BufferListStream.prototype, BufferList.prototype)
  
  BufferListStream.prototype._new = function _new (callback) {
    return new BufferListStream(callback)
  }
  
  BufferListStream.prototype._write = function _write (buf, encoding, callback) {
    this._appendBuffer(buf)
  
    if (typeof callback === 'function') {
      callback()
    }
  }
  
  BufferListStream.prototype._read = function _read (size) {
    if (!this.length) {
      return this.push(null)
    }
  
    size = Math.min(size, this.length)
    this.push(this.slice(0, size))
    this.consume(size)
  }
  
  BufferListStream.prototype.end = function end (chunk) {
    DuplexStream.prototype.end.call(this, chunk)
  
    if (this._callback) {
      this._callback(null, this.slice())
      this._callback = null
    }
  }
  
  BufferListStream.prototype._destroy = function _destroy (err, cb) {
    this._bufs.length = 0
    this.length = 0
    cb(err)
  }
  
  BufferListStream.prototype._isBufferList = function _isBufferList (b) {
    return b instanceof BufferListStream || b instanceof BufferList || BufferListStream.isBufferList(b)
  }
  
  BufferListStream.isBufferList = BufferList.isBufferList
  
  module.exports = BufferListStream
  module.exports.BufferListStream = BufferListStream
  module.exports.BufferList = BufferList
  
  },{"./BufferList":35,"inherits":29,"readable-stream":59}],37:[function(require,module,exports){
  (function (Buffer){
  const max = 65536
  const cache = {}
  
  // in node 6 Buffer.subarray returns a Uint8Array instead of a Buffer
  // later versions return a Buffer
  // alternative is Buffer.slice but that creates a new buffer
  // creating new buffers takes time
  // SubOk is only false on node < 8
  const SubOk = Buffer.isBuffer(Buffer.from([1, 2]).subarray(0, 1))
  
  function generateBuffer (i) {
    const buffer = Buffer.allocUnsafe(2)
    buffer.writeUInt8(i >> 8, 0)
    buffer.writeUInt8(i & 0x00FF, 0 + 1)
  
    return buffer
  }
  
  function generateCache () {
    for (let i = 0; i < max; i++) {
      cache[i] = generateBuffer(i)
    }
  }
  
  function genBufVariableByteInt (num) {
    const maxLength = 4 // max 4 bytes
    let digit = 0
    let pos = 0
    const buffer = Buffer.allocUnsafe(maxLength)
  
    do {
      digit = num % 128 | 0
      num = num / 128 | 0
      if (num > 0) digit = digit | 0x80
  
      buffer.writeUInt8(digit, pos++)
    } while (num > 0 && pos < maxLength)
  
    if (num > 0) {
      pos = 0
    }
  
    return SubOk ? buffer.subarray(0, pos) : buffer.slice(0, pos)
  }
  
  function generate4ByteBuffer (num) {
    const buffer = Buffer.allocUnsafe(4)
    buffer.writeUInt32BE(num, 0)
    return buffer
  }
  
  module.exports = {
    cache,
    generateCache,
    generateNumber: generateBuffer,
    genBufVariableByteInt,
    generate4ByteBuffer
  }
  
  }).call(this,require("buffer").Buffer)
  },{"buffer":12}],38:[function(require,module,exports){
  class Packet {
    constructor () {
      this.cmd = null
      this.retain = false
      this.qos = 0
      this.dup = false
      this.length = -1
      this.topic = null
      this.payload = null
    }
  }
  
  module.exports = Packet
  
  },{}],39:[function(require,module,exports){
  const bl = require('bl')
  const EventEmitter = require('events')
  const Packet = require('./packet')
  const constants = require('./constants')
  const debug = require('debug')('mqtt-packet:parser')
  
  class Parser extends EventEmitter {
    constructor () {
      super()
      this.parser = this.constructor.parser
    }
  
    static parser (opt) {
      if (!(this instanceof Parser)) return (new Parser()).parser(opt)
  
      this.settings = opt || {}
  
      this._states = [
        '_parseHeader',
        '_parseLength',
        '_parsePayload',
        '_newPacket'
      ]
  
      this._resetState()
      return this
    }
  
    _resetState () {
      debug('_resetState: resetting packet, error, _list, and _stateCounter')
      this.packet = new Packet()
      this.error = null
      this._list = bl()
      this._stateCounter = 0
    }
  
    parse (buf) {
      if (this.error) this._resetState()
  
      this._list.append(buf)
      debug('parse: current state: %s', this._states[this._stateCounter])
      while ((this.packet.length !== -1 || this._list.length > 0) &&
        this[this._states[this._stateCounter]]() &&
        !this.error) {
        this._stateCounter++
        debug('parse: state complete. _stateCounter is now: %d', this._stateCounter)
        debug('parse: packet.length: %d, buffer list length: %d', this.packet.length, this._list.length)
        if (this._stateCounter >= this._states.length) this._stateCounter = 0
      }
      debug('parse: exited while loop. packet: %d, buffer list length: %d', this.packet.length, this._list.length)
      return this._list.length
    }
  
    _parseHeader () {
      // There is at least one byte in the buffer
      const zero = this._list.readUInt8(0)
      this.packet.cmd = constants.types[zero >> constants.CMD_SHIFT]
      this.packet.retain = (zero & constants.RETAIN_MASK) !== 0
      this.packet.qos = (zero >> constants.QOS_SHIFT) & constants.QOS_MASK
      this.packet.dup = (zero & constants.DUP_MASK) !== 0
      debug('_parseHeader: packet: %o', this.packet)
  
      this._list.consume(1)
  
      return true
    }
  
    _parseLength () {
      // There is at least one byte in the list
      const result = this._parseVarByteNum(true)
  
      if (result) {
        this.packet.length = result.value
        this._list.consume(result.bytes)
      } else {
        this._emitError(new Error('Invalid length'))
      }
      debug('_parseLength %d', result.value)
      return !!result
    }
  
    _parsePayload () {
      debug('_parsePayload: payload %O', this._list)
      let result = false
  
      // Do we have a payload? Do we have enough data to complete the payload?
      // PINGs have no payload
      if (this.packet.length === 0 || this._list.length >= this.packet.length) {
        this._pos = 0
  
        switch (this.packet.cmd) {
          case 'connect':
            this._parseConnect()
            break
          case 'connack':
            this._parseConnack()
            break
          case 'publish':
            this._parsePublish()
            break
          case 'puback':
          case 'pubrec':
          case 'pubrel':
          case 'pubcomp':
            this._parseConfirmation()
            break
          case 'subscribe':
            this._parseSubscribe()
            break
          case 'suback':
            this._parseSuback()
            break
          case 'unsubscribe':
            this._parseUnsubscribe()
            break
          case 'unsuback':
            this._parseUnsuback()
            break
          case 'pingreq':
          case 'pingresp':
            // These are empty, nothing to do
            break
          case 'disconnect':
            this._parseDisconnect()
            break
          case 'auth':
            this._parseAuth()
            break
          default:
            this._emitError(new Error('Not supported'))
        }
  
        result = true
      }
      debug('_parsePayload complete result: %s', result)
      return result
    }
  
    _parseConnect () {
      debug('_parseConnect')
      let topic // Will topic
      let payload // Will payload
      let password // Password
      let username // Username
      const flags = {}
      const packet = this.packet
  
      // Parse protocolId
      const protocolId = this._parseString()
  
      if (protocolId === null) return this._emitError(new Error('Cannot parse protocolId'))
      if (protocolId !== 'MQTT' && protocolId !== 'MQIsdp') {
        return this._emitError(new Error('Invalid protocolId'))
      }
  
      packet.protocolId = protocolId
  
      // Parse constants version number
      if (this._pos >= this._list.length) return this._emitError(new Error('Packet too short'))
  
      packet.protocolVersion = this._list.readUInt8(this._pos)
  
      if (packet.protocolVersion !== 3 && packet.protocolVersion !== 4 && packet.protocolVersion !== 5) {
        return this._emitError(new Error('Invalid protocol version'))
      }
  
      this._pos++
  
      if (this._pos >= this._list.length) {
        return this._emitError(new Error('Packet too short'))
      }
  
      // Parse connect flags
      flags.username = (this._list.readUInt8(this._pos) & constants.USERNAME_MASK)
      flags.password = (this._list.readUInt8(this._pos) & constants.PASSWORD_MASK)
      flags.will = (this._list.readUInt8(this._pos) & constants.WILL_FLAG_MASK)
  
      if (flags.will) {
        packet.will = {}
        packet.will.retain = (this._list.readUInt8(this._pos) & constants.WILL_RETAIN_MASK) !== 0
        packet.will.qos = (this._list.readUInt8(this._pos) &
          constants.WILL_QOS_MASK) >> constants.WILL_QOS_SHIFT
      }
  
      packet.clean = (this._list.readUInt8(this._pos) & constants.CLEAN_SESSION_MASK) !== 0
      this._pos++
  
      // Parse keepalive
      packet.keepalive = this._parseNum()
      if (packet.keepalive === -1) return this._emitError(new Error('Packet too short'))
  
      // parse properties
      if (packet.protocolVersion === 5) {
        const properties = this._parseProperties()
        if (Object.getOwnPropertyNames(properties).length) {
          packet.properties = properties
        }
      }
      // Parse clientId
      const clientId = this._parseString()
      if (clientId === null) return this._emitError(new Error('Packet too short'))
      packet.clientId = clientId
      debug('_parseConnect: packet.clientId: %s', packet.clientId)
  
      if (flags.will) {
        if (packet.protocolVersion === 5) {
          const willProperties = this._parseProperties()
          if (Object.getOwnPropertyNames(willProperties).length) {
            packet.will.properties = willProperties
          }
        }
        // Parse will topic
        topic = this._parseString()
        if (topic === null) return this._emitError(new Error('Cannot parse will topic'))
        packet.will.topic = topic
        debug('_parseConnect: packet.will.topic: %s', packet.will.topic)
  
        // Parse will payload
        payload = this._parseBuffer()
        if (payload === null) return this._emitError(new Error('Cannot parse will payload'))
        packet.will.payload = payload
        debug('_parseConnect: packet.will.paylaod: %s', packet.will.payload)
      }
  
      // Parse username
      if (flags.username) {
        username = this._parseString()
        if (username === null) return this._emitError(new Error('Cannot parse username'))
        packet.username = username
        debug('_parseConnect: packet.username: %s', packet.username)
      }
  
      // Parse password
      if (flags.password) {
        password = this._parseBuffer()
        if (password === null) return this._emitError(new Error('Cannot parse password'))
        packet.password = password
      }
      // need for right parse auth packet and self set up
      this.settings = packet
      debug('_parseConnect: complete')
      return packet
    }
  
    _parseConnack () {
      debug('_parseConnack')
      const packet = this.packet
  
      if (this._list.length < 2) return null
  
      packet.sessionPresent = !!(this._list.readUInt8(this._pos++) & constants.SESSIONPRESENT_MASK)
      if (this.settings.protocolVersion === 5) {
        packet.reasonCode = this._list.readUInt8(this._pos++)
      } else {
        packet.returnCode = this._list.readUInt8(this._pos++)
      }
  
      if (packet.returnCode === -1 || packet.reasonCode === -1) return this._emitError(new Error('Cannot parse return code'))
      // mqtt 5 properties
      if (this.settings.protocolVersion === 5) {
        const properties = this._parseProperties()
        if (Object.getOwnPropertyNames(properties).length) {
          packet.properties = properties
        }
      }
      debug('_parseConnack: complete')
    }
  
    _parsePublish () {
      debug('_parsePublish')
      const packet = this.packet
      packet.topic = this._parseString()
  
      if (packet.topic === null) return this._emitError(new Error('Cannot parse topic'))
  
      // Parse messageId
      if (packet.qos > 0) if (!this._parseMessageId()) { return }
  
      // Properties mqtt 5
      if (this.settings.protocolVersion === 5) {
        const properties = this._parseProperties()
        if (Object.getOwnPropertyNames(properties).length) {
          packet.properties = properties
        }
      }
  
      packet.payload = this._list.slice(this._pos, packet.length)
      debug('_parsePublish: payload from buffer list: %o', packet.payload)
    }
  
    _parseSubscribe () {
      debug('_parseSubscribe')
      const packet = this.packet
      let topic
      let options
      let qos
      let rh
      let rap
      let nl
      let subscription
  
      if (packet.qos !== 1) {
        return this._emitError(new Error('Wrong subscribe header'))
      }
  
      packet.subscriptions = []
  
      if (!this._parseMessageId()) { return }
  
      // Properties mqtt 5
      if (this.settings.protocolVersion === 5) {
        const properties = this._parseProperties()
        if (Object.getOwnPropertyNames(properties).length) {
          packet.properties = properties
        }
      }
  
      while (this._pos < packet.length) {
        // Parse topic
        topic = this._parseString()
        if (topic === null) return this._emitError(new Error('Cannot parse topic'))
        if (this._pos >= packet.length) return this._emitError(new Error('Malformed Subscribe Payload'))
  
        options = this._parseByte()
        qos = options & constants.SUBSCRIBE_OPTIONS_QOS_MASK
        nl = ((options >> constants.SUBSCRIBE_OPTIONS_NL_SHIFT) & constants.SUBSCRIBE_OPTIONS_NL_MASK) !== 0
        rap = ((options >> constants.SUBSCRIBE_OPTIONS_RAP_SHIFT) & constants.SUBSCRIBE_OPTIONS_RAP_MASK) !== 0
        rh = (options >> constants.SUBSCRIBE_OPTIONS_RH_SHIFT) & constants.SUBSCRIBE_OPTIONS_RH_MASK
  
        subscription = { topic, qos }
  
        // mqtt 5 options
        if (this.settings.protocolVersion === 5) {
          subscription.nl = nl
          subscription.rap = rap
          subscription.rh = rh
        }
  
        // Push pair to subscriptions
        debug('_parseSubscribe: push subscription `%s` to subscription', subscription)
        packet.subscriptions.push(subscription)
      }
    }
  
    _parseSuback () {
      debug('_parseSuback')
      const packet = this.packet
      this.packet.granted = []
  
      if (!this._parseMessageId()) { return }
  
      // Properties mqtt 5
      if (this.settings.protocolVersion === 5) {
        const properties = this._parseProperties()
        if (Object.getOwnPropertyNames(properties).length) {
          packet.properties = properties
        }
      }
  
      // Parse granted QoSes
      while (this._pos < this.packet.length) {
        this.packet.granted.push(this._list.readUInt8(this._pos++))
      }
    }
  
    _parseUnsubscribe () {
      debug('_parseUnsubscribe')
      const packet = this.packet
  
      packet.unsubscriptions = []
  
      // Parse messageId
      if (!this._parseMessageId()) { return }
  
      // Properties mqtt 5
      if (this.settings.protocolVersion === 5) {
        const properties = this._parseProperties()
        if (Object.getOwnPropertyNames(properties).length) {
          packet.properties = properties
        }
      }
  
      while (this._pos < packet.length) {
        // Parse topic
        const topic = this._parseString()
        if (topic === null) return this._emitError(new Error('Cannot parse topic'))
  
        // Push topic to unsubscriptions
        debug('_parseUnsubscribe: push topic `%s` to unsubscriptions', topic)
        packet.unsubscriptions.push(topic)
      }
    }
  
    _parseUnsuback () {
      debug('_parseUnsuback')
      const packet = this.packet
      if (!this._parseMessageId()) return this._emitError(new Error('Cannot parse messageId'))
      // Properties mqtt 5
      if (this.settings.protocolVersion === 5) {
        const properties = this._parseProperties()
        if (Object.getOwnPropertyNames(properties).length) {
          packet.properties = properties
        }
        // Parse granted QoSes
        packet.granted = []
        while (this._pos < this.packet.length) {
          this.packet.granted.push(this._list.readUInt8(this._pos++))
        }
      }
    }
  
    // parse packets like puback, pubrec, pubrel, pubcomp
    _parseConfirmation () {
      debug('_parseConfirmation: packet.cmd: `%s`', this.packet.cmd)
      const packet = this.packet
  
      this._parseMessageId()
  
      if (this.settings.protocolVersion === 5) {
        if (packet.length > 2) {
          // response code
          packet.reasonCode = this._parseByte()
          debug('_parseConfirmation: packet.reasonCode `%d`', packet.reasonCode)
        }
  
        if (packet.length > 3) {
          // properies mqtt 5
          const properties = this._parseProperties()
          if (Object.getOwnPropertyNames(properties).length) {
            packet.properties = properties
          }
        }
      }
  
      return true
    }
  
    // parse disconnect packet
    _parseDisconnect () {
      const packet = this.packet
      debug('_parseDisconnect')
  
      if (this.settings.protocolVersion === 5) {
        // response code
        packet.reasonCode = this._parseByte()
        // properies mqtt 5
        const properties = this._parseProperties()
        if (Object.getOwnPropertyNames(properties).length) {
          packet.properties = properties
        }
      }
  
      debug('_parseDisconnect result: true')
      return true
    }
  
    // parse auth packet
    _parseAuth () {
      debug('_parseAuth')
      const packet = this.packet
  
      if (this.settings.protocolVersion !== 5) {
        return this._emitError(new Error('Not supported auth packet for this version MQTT'))
      }
  
      // response code
      packet.reasonCode = this._parseByte()
      // properies mqtt 5
      const properties = this._parseProperties()
      if (Object.getOwnPropertyNames(properties).length) {
        packet.properties = properties
      }
  
      debug('_parseAuth: result: true')
      return true
    }
  
    _parseMessageId () {
      const packet = this.packet
  
      packet.messageId = this._parseNum()
  
      if (packet.messageId === null) {
        this._emitError(new Error('Cannot parse messageId'))
        return false
      }
  
      debug('_parseMessageId: packet.messageId %d', packet.messageId)
      return true
    }
  
    _parseString (maybeBuffer) {
      const length = this._parseNum()
      const end = length + this._pos
  
      if (length === -1 || end > this._list.length || end > this.packet.length) return null
  
      const result = this._list.toString('utf8', this._pos, end)
      this._pos += length
      debug('_parseString: result: %s', result)
      return result
    }
  
    _parseStringPair () {
      debug('_parseStringPair')
      return {
        name: this._parseString(),
        value: this._parseString()
      }
    }
  
    _parseBuffer () {
      const length = this._parseNum()
      const end = length + this._pos
  
      if (length === -1 || end > this._list.length || end > this.packet.length) return null
  
      const result = this._list.slice(this._pos, end)
  
      this._pos += length
      debug('_parseBuffer: result: %o', result)
      return result
    }
  
    _parseNum () {
      if (this._list.length - this._pos < 2) return -1
  
      const result = this._list.readUInt16BE(this._pos)
      this._pos += 2
      debug('_parseNum: result: %s', result)
      return result
    }
  
    _parse4ByteNum () {
      if (this._list.length - this._pos < 4) return -1
  
      const result = this._list.readUInt32BE(this._pos)
      this._pos += 4
      debug('_parse4ByteNum: result: %s', result)
      return result
    }
  
    _parseVarByteNum (fullInfoFlag) {
      debug('_parseVarByteNum')
      let bytes = 0
      let mul = 1
      let value = 0
      let result = false
      let current
      const padding = this._pos ? this._pos : 0
  
      while (bytes < 5) {
        current = this._list.readUInt8(padding + bytes++)
        value += mul * (current & constants.VARBYTEINT_MASK)
        mul *= 0x80
  
        if ((current & constants.VARBYTEINT_FIN_MASK) === 0) {
          result = true
          break
        }
        if (this._list.length <= bytes) {
          break
        }
      }
  
      if (padding) {
        this._pos += bytes
      }
  
      result = result
        ? fullInfoFlag ? {
          bytes,
          value
        } : value
        : false
  
      debug('_parseVarByteNum: result: %o', result)
      return result
    }
  
    _parseByte () {
      const result = this._list.readUInt8(this._pos)
      this._pos++
      debug('_parseByte: result: %o', result)
      return result
    }
  
    _parseByType (type) {
      debug('_parseByType: type: %s', type)
      switch (type) {
        case 'byte': {
          return this._parseByte() !== 0
        }
        case 'int8': {
          return this._parseByte()
        }
        case 'int16': {
          return this._parseNum()
        }
        case 'int32': {
          return this._parse4ByteNum()
        }
        case 'var': {
          return this._parseVarByteNum()
        }
        case 'string': {
          return this._parseString()
        }
        case 'pair': {
          return this._parseStringPair()
        }
        case 'binary': {
          return this._parseBuffer()
        }
      }
    }
  
    _parseProperties () {
      debug('_parseProperties')
      const length = this._parseVarByteNum()
      const start = this._pos
      const end = start + length
      const result = {}
      while (this._pos < end) {
        const type = this._parseByte()
        const name = constants.propertiesCodes[type]
        if (!name) {
          this._emitError(new Error('Unknown property'))
          return false
        }
        // user properties process
        if (name === 'userProperties') {
          if (!result[name]) {
            result[name] = Object.create(null)
          }
          const currentUserProperty = this._parseByType(constants.propertiesTypes[name])
          if (result[name][currentUserProperty.name]) {
            if (Array.isArray(result[name][currentUserProperty.name])) {
              result[name][currentUserProperty.name].push(currentUserProperty.value)
            } else {
              const currentValue = result[name][currentUserProperty.name]
              result[name][currentUserProperty.name] = [currentValue]
              result[name][currentUserProperty.name].push(currentUserProperty.value)
            }
          } else {
            result[name][currentUserProperty.name] = currentUserProperty.value
          }
          continue
        }
        if (result[name]) {
          if (Array.isArray(result[name])) {
            result[name].push(this._parseByType(constants.propertiesTypes[name]))
          } else {
            result[name] = [result[name]]
            result[name].push(this._parseByType(constants.propertiesTypes[name]))
          }
        } else {
          result[name] = this._parseByType(constants.propertiesTypes[name])
        }
      }
      return result
    }
  
    _newPacket () {
      debug('_newPacket')
      if (this.packet) {
        this._list.consume(this.packet.length)
        debug('_newPacket: parser emit packet: packet.cmd: %s, packet.payload: %s, packet.length: %d', this.packet.cmd, this.packet.payload, this.packet.length)
        this.emit('packet', this.packet)
      }
      debug('_newPacket: new packet')
      this.packet = new Packet()
  
      this._pos = 0
  
      return true
    }
  
    _emitError (err) {
      debug('_emitError')
      this.error = err
      this.emit('error', err)
    }
  }
  
  module.exports = Parser
  
  },{"./constants":32,"./packet":38,"bl":36,"debug":14,"events":27}],40:[function(require,module,exports){
  (function (Buffer){
  const protocol = require('./constants')
  const empty = Buffer.allocUnsafe(0)
  const zeroBuf = Buffer.from([0])
  const numbers = require('./numbers')
  const nextTick = require('process-nextick-args').nextTick
  const debug = require('debug')('mqtt-packet:writeToStream')
  
  const numCache = numbers.cache
  const generateNumber = numbers.generateNumber
  const generateCache = numbers.generateCache
  const genBufVariableByteInt = numbers.genBufVariableByteInt
  const generate4ByteBuffer = numbers.generate4ByteBuffer
  let writeNumber = writeNumberCached
  let toGenerate = true
  
  function generate (packet, stream, opts) {
    debug('generate called')
    if (stream.cork) {
      stream.cork()
      nextTick(uncork, stream)
    }
  
    if (toGenerate) {
      toGenerate = false
      generateCache()
    }
    debug('generate: packet.cmd: %s', packet.cmd)
    switch (packet.cmd) {
      case 'connect':
        return connect(packet, stream, opts)
      case 'connack':
        return connack(packet, stream, opts)
      case 'publish':
        return publish(packet, stream, opts)
      case 'puback':
      case 'pubrec':
      case 'pubrel':
      case 'pubcomp':
        return confirmation(packet, stream, opts)
      case 'subscribe':
        return subscribe(packet, stream, opts)
      case 'suback':
        return suback(packet, stream, opts)
      case 'unsubscribe':
        return unsubscribe(packet, stream, opts)
      case 'unsuback':
        return unsuback(packet, stream, opts)
      case 'pingreq':
      case 'pingresp':
        return emptyPacket(packet, stream, opts)
      case 'disconnect':
        return disconnect(packet, stream, opts)
      case 'auth':
        return auth(packet, stream, opts)
      default:
        stream.emit('error', new Error('Unknown command'))
        return false
    }
  }
  /**
   * Controls numbers cache.
   * Set to "false" to allocate buffers on-the-flight instead of pre-generated cache
   */
  Object.defineProperty(generate, 'cacheNumbers', {
    get () {
      return writeNumber === writeNumberCached
    },
    set (value) {
      if (value) {
        if (!numCache || Object.keys(numCache).length === 0) toGenerate = true
        writeNumber = writeNumberCached
      } else {
        toGenerate = false
        writeNumber = writeNumberGenerated
      }
    }
  })
  
  function uncork (stream) {
    stream.uncork()
  }
  
  function connect (packet, stream, opts) {
    const settings = packet || {}
    const protocolId = settings.protocolId || 'MQTT'
    const protocolVersion = settings.protocolVersion || 4
    const will = settings.will
    let clean = settings.clean
    const keepalive = settings.keepalive || 0
    const clientId = settings.clientId || ''
    const username = settings.username
    const password = settings.password
    /* mqtt5 new oprions */
    const properties = settings.properties
  
    if (clean === undefined) clean = true
  
    let length = 0
  
    // Must be a string and non-falsy
    if (!protocolId ||
       (typeof protocolId !== 'string' && !Buffer.isBuffer(protocolId))) {
      stream.emit('error', new Error('Invalid protocolId'))
      return false
    } else length += protocolId.length + 2
  
    // Must be 3 or 4 or 5
    if (protocolVersion !== 3 && protocolVersion !== 4 && protocolVersion !== 5) {
      stream.emit('error', new Error('Invalid protocol version'))
      return false
    } else length += 1
  
    // ClientId might be omitted in 3.1.1, but only if cleanSession is set to 1
    if ((typeof clientId === 'string' || Buffer.isBuffer(clientId)) &&
       (clientId || protocolVersion === 4) && (clientId || clean)) {
      length += clientId.length + 2
    } else {
      if (protocolVersion < 4) {
        stream.emit('error', new Error('clientId must be supplied before 3.1.1'))
        return false
      }
      if ((clean * 1) === 0) {
        stream.emit('error', new Error('clientId must be given if cleanSession set to 0'))
        return false
      }
    }
  
    // Must be a two byte number
    if (typeof keepalive !== 'number' ||
        keepalive < 0 ||
        keepalive > 65535 ||
        keepalive % 1 !== 0) {
      stream.emit('error', new Error('Invalid keepalive'))
      return false
    } else length += 2
  
    // Connect flags
    length += 1
  
    // Properties
    if (protocolVersion === 5) {
      var propertiesData = getProperties(stream, properties)
      if (!propertiesData) { return false }
      length += propertiesData.length
    }
  
    // If will exists...
    if (will) {
      // It must be an object
      if (typeof will !== 'object') {
        stream.emit('error', new Error('Invalid will'))
        return false
      }
      // It must have topic typeof string
      if (!will.topic || typeof will.topic !== 'string') {
        stream.emit('error', new Error('Invalid will topic'))
        return false
      } else {
        length += Buffer.byteLength(will.topic) + 2
      }
  
      // Payload
      length += 2 // payload length
      if (will.payload) {
        if (will.payload.length >= 0) {
          if (typeof will.payload === 'string') {
            length += Buffer.byteLength(will.payload)
          } else {
            length += will.payload.length
          }
        } else {
          stream.emit('error', new Error('Invalid will payload'))
          return false
        }
      }
      // will properties
      var willProperties = {}
      if (protocolVersion === 5) {
        willProperties = getProperties(stream, will.properties)
        if (!willProperties) { return false }
        length += willProperties.length
      }
    }
  
    // Username
    let providedUsername = false
    if (username != null) {
      if (isStringOrBuffer(username)) {
        providedUsername = true
        length += Buffer.byteLength(username) + 2
      } else {
        stream.emit('error', new Error('Invalid username'))
        return false
      }
    }
  
    // Password
    if (password != null) {
      if (!providedUsername) {
        stream.emit('error', new Error('Username is required to use password'))
        return false
      }
  
      if (isStringOrBuffer(password)) {
        length += byteLength(password) + 2
      } else {
        stream.emit('error', new Error('Invalid password'))
        return false
      }
    }
  
    // Generate header
    stream.write(protocol.CONNECT_HEADER)
  
    // Generate length
    writeVarByteInt(stream, length)
  
    // Generate protocol ID
    writeStringOrBuffer(stream, protocolId)
    stream.write(
      protocolVersion === 4
        ? protocol.VERSION4
        : protocolVersion === 5
          ? protocol.VERSION5
          : protocol.VERSION3
    )
  
    // Connect flags
    let flags = 0
    flags |= (username != null) ? protocol.USERNAME_MASK : 0
    flags |= (password != null) ? protocol.PASSWORD_MASK : 0
    flags |= (will && will.retain) ? protocol.WILL_RETAIN_MASK : 0
    flags |= (will && will.qos) ? will.qos << protocol.WILL_QOS_SHIFT : 0
    flags |= will ? protocol.WILL_FLAG_MASK : 0
    flags |= clean ? protocol.CLEAN_SESSION_MASK : 0
  
    stream.write(Buffer.from([flags]))
  
    // Keepalive
    writeNumber(stream, keepalive)
  
    // Properties
    if (protocolVersion === 5) {
      propertiesData.write()
    }
  
    // Client ID
    writeStringOrBuffer(stream, clientId)
  
    // Will
    if (will) {
      if (protocolVersion === 5) {
        willProperties.write()
      }
      writeString(stream, will.topic)
      writeStringOrBuffer(stream, will.payload)
    }
  
    // Username and password
    if (username != null) {
      writeStringOrBuffer(stream, username)
    }
    if (password != null) {
      writeStringOrBuffer(stream, password)
    }
    // This is a small packet that happens only once on a stream
    // We assume the stream is always free to receive more data after this
    return true
  }
  
  function connack (packet, stream, opts) {
    const version = opts ? opts.protocolVersion : 4
    const settings = packet || {}
    const rc = version === 5 ? settings.reasonCode : settings.returnCode
    const properties = settings.properties
    let length = 2 // length of rc and sessionHeader
  
    // Check return code
    if (typeof rc !== 'number') {
      stream.emit('error', new Error('Invalid return code'))
      return false
    }
    // mqtt5 properties
    let propertiesData = null
    if (version === 5) {
      propertiesData = getProperties(stream, properties)
      if (!propertiesData) { return false }
      length += propertiesData.length
    }
  
    stream.write(protocol.CONNACK_HEADER)
    // length
    writeVarByteInt(stream, length)
    stream.write(settings.sessionPresent ? protocol.SESSIONPRESENT_HEADER : zeroBuf)
  
    stream.write(Buffer.from([rc]))
    if (propertiesData != null) {
      propertiesData.write()
    }
    return true
  }
  
  function publish (packet, stream, opts) {
    debug('publish: packet: %o', packet)
    const version = opts ? opts.protocolVersion : 4
    const settings = packet || {}
    const qos = settings.qos || 0
    const retain = settings.retain ? protocol.RETAIN_MASK : 0
    const topic = settings.topic
    const payload = settings.payload || empty
    const id = settings.messageId
    const properties = settings.properties
  
    let length = 0
  
    // Topic must be a non-empty string or Buffer
    if (typeof topic === 'string') length += Buffer.byteLength(topic) + 2
    else if (Buffer.isBuffer(topic)) length += topic.length + 2
    else {
      stream.emit('error', new Error('Invalid topic'))
      return false
    }
  
    // Get the payload length
    if (!Buffer.isBuffer(payload)) length += Buffer.byteLength(payload)
    else length += payload.length
  
    // Message ID must a number if qos > 0
    if (qos && typeof id !== 'number') {
      stream.emit('error', new Error('Invalid messageId'))
      return false
    } else if (qos) length += 2
  
    // mqtt5 properties
    let propertiesData = null
    if (version === 5) {
      propertiesData = getProperties(stream, properties)
      if (!propertiesData) { return false }
      length += propertiesData.length
    }
  
    // Header
    stream.write(protocol.PUBLISH_HEADER[qos][settings.dup ? 1 : 0][retain ? 1 : 0])
  
    // Remaining length
    writeVarByteInt(stream, length)
  
    // Topic
    writeNumber(stream, byteLength(topic))
    stream.write(topic)
  
    // Message ID
    if (qos > 0) writeNumber(stream, id)
  
    // Properties
    if (propertiesData != null) {
      propertiesData.write()
    }
  
    // Payload
    debug('publish: payload: %o', payload)
    return stream.write(payload)
  }
  
  /* Puback, pubrec, pubrel and pubcomp */
  function confirmation (packet, stream, opts) {
    const version = opts ? opts.protocolVersion : 4
    const settings = packet || {}
    const type = settings.cmd || 'puback'
    const id = settings.messageId
    const dup = (settings.dup && type === 'pubrel') ? protocol.DUP_MASK : 0
    let qos = 0
    const reasonCode = settings.reasonCode
    const properties = settings.properties
    let length = version === 5 ? 3 : 2
  
    if (type === 'pubrel') qos = 1
  
    // Check message ID
    if (typeof id !== 'number') {
      stream.emit('error', new Error('Invalid messageId'))
      return false
    }
  
    // properies mqtt 5
    let propertiesData = null
    if (version === 5) {
      // Confirm should not add empty property length with no properties (rfc 3.4.2.2.1)
      if (typeof properties === 'object') {
        propertiesData = getPropertiesByMaximumPacketSize(stream, properties, opts, length)
        if (!propertiesData) { return false }
        length += propertiesData.length
      }
    }
  
    // Header
    stream.write(protocol.ACKS[type][qos][dup][0])
  
    // Length
    writeVarByteInt(stream, length)
  
    // Message ID
    writeNumber(stream, id)
  
    // reason code in header
    if (version === 5) {
      stream.write(Buffer.from([reasonCode]))
    }
  
    // properies mqtt 5
    if (propertiesData !== null) {
      propertiesData.write()
    }
    return true
  }
  
  function subscribe (packet, stream, opts) {
    debug('subscribe: packet: ')
    const version = opts ? opts.protocolVersion : 4
    const settings = packet || {}
    const dup = settings.dup ? protocol.DUP_MASK : 0
    const id = settings.messageId
    const subs = settings.subscriptions
    const properties = settings.properties
  
    let length = 0
  
    // Check message ID
    if (typeof id !== 'number') {
      stream.emit('error', new Error('Invalid messageId'))
      return false
    } else length += 2
  
    // properies mqtt 5
    let propertiesData = null
    if (version === 5) {
      propertiesData = getProperties(stream, properties)
      if (!propertiesData) { return false }
      length += propertiesData.length
    }
  
    // Check subscriptions
    if (typeof subs === 'object' && subs.length) {
      for (let i = 0; i < subs.length; i += 1) {
        const itopic = subs[i].topic
        const iqos = subs[i].qos
  
        if (typeof itopic !== 'string') {
          stream.emit('error', new Error('Invalid subscriptions - invalid topic'))
          return false
        }
        if (typeof iqos !== 'number') {
          stream.emit('error', new Error('Invalid subscriptions - invalid qos'))
          return false
        }
  
        if (version === 5) {
          const nl = subs[i].nl || false
          if (typeof nl !== 'boolean') {
            stream.emit('error', new Error('Invalid subscriptions - invalid No Local'))
            return false
          }
          const rap = subs[i].rap || false
          if (typeof rap !== 'boolean') {
            stream.emit('error', new Error('Invalid subscriptions - invalid Retain as Published'))
            return false
          }
          const rh = subs[i].rh || 0
          if (typeof rh !== 'number' || rh > 2) {
            stream.emit('error', new Error('Invalid subscriptions - invalid Retain Handling'))
            return false
          }
        }
  
        length += Buffer.byteLength(itopic) + 2 + 1
      }
    } else {
      stream.emit('error', new Error('Invalid subscriptions'))
      return false
    }
  
    // Generate header
    debug('subscribe: writing to stream: %o', protocol.SUBSCRIBE_HEADER)
    stream.write(protocol.SUBSCRIBE_HEADER[1][dup ? 1 : 0][0])
  
    // Generate length
    writeVarByteInt(stream, length)
  
    // Generate message ID
    writeNumber(stream, id)
  
    // properies mqtt 5
    if (propertiesData !== null) {
      propertiesData.write()
    }
  
    let result = true
  
    // Generate subs
    for (const sub of subs) {
      const jtopic = sub.topic
      const jqos = sub.qos
      const jnl = +sub.nl
      const jrap = +sub.rap
      const jrh = sub.rh
      let joptions
  
      // Write topic string
      writeString(stream, jtopic)
  
      // options process
      joptions = protocol.SUBSCRIBE_OPTIONS_QOS[jqos]
      if (version === 5) {
        joptions |= jnl ? protocol.SUBSCRIBE_OPTIONS_NL : 0
        joptions |= jrap ? protocol.SUBSCRIBE_OPTIONS_RAP : 0
        joptions |= jrh ? protocol.SUBSCRIBE_OPTIONS_RH[jrh] : 0
      }
      // Write options
      result = stream.write(Buffer.from([joptions]))
    }
  
    return result
  }
  
  function suback (packet, stream, opts) {
    const version = opts ? opts.protocolVersion : 4
    const settings = packet || {}
    const id = settings.messageId
    const granted = settings.granted
    const properties = settings.properties
    let length = 0
  
    // Check message ID
    if (typeof id !== 'number') {
      stream.emit('error', new Error('Invalid messageId'))
      return false
    } else length += 2
  
    // Check granted qos vector
    if (typeof granted === 'object' && granted.length) {
      for (let i = 0; i < granted.length; i += 1) {
        if (typeof granted[i] !== 'number') {
          stream.emit('error', new Error('Invalid qos vector'))
          return false
        }
        length += 1
      }
    } else {
      stream.emit('error', new Error('Invalid qos vector'))
      return false
    }
  
    // properies mqtt 5
    let propertiesData = null
    if (version === 5) {
      propertiesData = getPropertiesByMaximumPacketSize(stream, properties, opts, length)
      if (!propertiesData) { return false }
      length += propertiesData.length
    }
  
    // header
    stream.write(protocol.SUBACK_HEADER)
  
    // Length
    writeVarByteInt(stream, length)
  
    // Message ID
    writeNumber(stream, id)
  
    // properies mqtt 5
    if (propertiesData !== null) {
      propertiesData.write()
    }
  
    return stream.write(Buffer.from(granted))
  }
  
  function unsubscribe (packet, stream, opts) {
    const version = opts ? opts.protocolVersion : 4
    const settings = packet || {}
    const id = settings.messageId
    const dup = settings.dup ? protocol.DUP_MASK : 0
    const unsubs = settings.unsubscriptions
    const properties = settings.properties
  
    let length = 0
  
    // Check message ID
    if (typeof id !== 'number') {
      stream.emit('error', new Error('Invalid messageId'))
      return false
    } else {
      length += 2
    }
    // Check unsubs
    if (typeof unsubs === 'object' && unsubs.length) {
      for (let i = 0; i < unsubs.length; i += 1) {
        if (typeof unsubs[i] !== 'string') {
          stream.emit('error', new Error('Invalid unsubscriptions'))
          return false
        }
        length += Buffer.byteLength(unsubs[i]) + 2
      }
    } else {
      stream.emit('error', new Error('Invalid unsubscriptions'))
      return false
    }
    // properies mqtt 5
    let propertiesData = null
    if (version === 5) {
      propertiesData = getProperties(stream, properties)
      if (!propertiesData) { return false }
      length += propertiesData.length
    }
  
    // Header
    stream.write(protocol.UNSUBSCRIBE_HEADER[1][dup ? 1 : 0][0])
  
    // Length
    writeVarByteInt(stream, length)
  
    // Message ID
    writeNumber(stream, id)
  
    // properies mqtt 5
    if (propertiesData !== null) {
      propertiesData.write()
    }
  
    // Unsubs
    let result = true
    for (let j = 0; j < unsubs.length; j++) {
      result = writeString(stream, unsubs[j])
    }
  
    return result
  }
  
  function unsuback (packet, stream, opts) {
    const version = opts ? opts.protocolVersion : 4
    const settings = packet || {}
    const id = settings.messageId
    const dup = settings.dup ? protocol.DUP_MASK : 0
    const granted = settings.granted
    const properties = settings.properties
    const type = settings.cmd
    const qos = 0
  
    let length = 2
  
    // Check message ID
    if (typeof id !== 'number') {
      stream.emit('error', new Error('Invalid messageId'))
      return false
    }
  
    // Check granted
    if (version === 5) {
      if (typeof granted === 'object' && granted.length) {
        for (let i = 0; i < granted.length; i += 1) {
          if (typeof granted[i] !== 'number') {
            stream.emit('error', new Error('Invalid qos vector'))
            return false
          }
          length += 1
        }
      } else {
        stream.emit('error', new Error('Invalid qos vector'))
        return false
      }
    }
  
    // properies mqtt 5
    let propertiesData = null
    if (version === 5) {
      propertiesData = getPropertiesByMaximumPacketSize(stream, properties, opts, length)
      if (!propertiesData) { return false }
      length += propertiesData.length
    }
  
    // Header
    stream.write(protocol.ACKS[type][qos][dup][0])
  
    // Length
    writeVarByteInt(stream, length)
  
    // Message ID
    writeNumber(stream, id)
  
    // properies mqtt 5
    if (propertiesData !== null) {
      propertiesData.write()
    }
  
    // payload
    if (version === 5) {
      stream.write(Buffer.from(granted))
    }
    return true
  }
  
  function emptyPacket (packet, stream, opts) {
    return stream.write(protocol.EMPTY[packet.cmd])
  }
  
  function disconnect (packet, stream, opts) {
    const version = opts ? opts.protocolVersion : 4
    const settings = packet || {}
    const reasonCode = settings.reasonCode
    const properties = settings.properties
    let length = version === 5 ? 1 : 0
  
    // properies mqtt 5
    let propertiesData = null
    if (version === 5) {
      propertiesData = getPropertiesByMaximumPacketSize(stream, properties, opts, length)
      if (!propertiesData) { return false }
      length += propertiesData.length
    }
  
    // Header
    stream.write(Buffer.from([protocol.codes.disconnect << 4]))
  
    // Length
    writeVarByteInt(stream, length)
  
    // reason code in header
    if (version === 5) {
      stream.write(Buffer.from([reasonCode]))
    }
  
    // properies mqtt 5
    if (propertiesData !== null) {
      propertiesData.write()
    }
  
    return true
  }
  
  function auth (packet, stream, opts) {
    const version = opts ? opts.protocolVersion : 4
    const settings = packet || {}
    const reasonCode = settings.reasonCode
    const properties = settings.properties
    let length = version === 5 ? 1 : 0
  
    if (version !== 5) stream.emit('error', new Error('Invalid mqtt version for auth packet'))
  
    // properies mqtt 5
    const propertiesData = getPropertiesByMaximumPacketSize(stream, properties, opts, length)
    if (!propertiesData) { return false }
    length += propertiesData.length
  
    // Header
    stream.write(Buffer.from([protocol.codes.auth << 4]))
  
    // Length
    writeVarByteInt(stream, length)
  
    // reason code in header
    stream.write(Buffer.from([reasonCode]))
  
    // properies mqtt 5
    if (propertiesData !== null) {
      propertiesData.write()
    }
    return true
  }
  
  /**
   * writeVarByteInt - write an MQTT style variable byte integer to the buffer
   *
   * @param <Buffer> buffer - destination
   * @param <Number> pos - offset
   * @param <Number> length - length (>0)
   * @returns <Number> number of bytes written
   *
   * @api private
   */
  
  const varByteIntCache = {}
  function writeVarByteInt (stream, num) {
    let buffer = varByteIntCache[num]
  
    if (!buffer) {
      buffer = genBufVariableByteInt(num)
      if (num < 16384) varByteIntCache[num] = buffer
    }
    debug('writeVarByteInt: writing to stream: %o', buffer)
    stream.write(buffer)
  }
  
  /**
   * writeString - write a utf8 string to the buffer
   *
   * @param <Buffer> buffer - destination
   * @param <Number> pos - offset
   * @param <String> string - string to write
   * @return <Number> number of bytes written
   *
   * @api private
   */
  
  function writeString (stream, string) {
    const strlen = Buffer.byteLength(string)
    writeNumber(stream, strlen)
  
    debug('writeString: %s', string)
    return stream.write(string, 'utf8')
  }
  
  /**
   * writeStringPair - write a utf8 string pairs to the buffer
   *
   * @param <Buffer> buffer - destination
   * @param <String> name - string name to write
   * @param <String> value - string value to write
   * @return <Number> number of bytes written
   *
   * @api private
   */
  function writeStringPair (stream, name, value) {
    writeString(stream, name)
    writeString(stream, value)
  }
  
  /**
   * writeNumber - write a two byte number to the buffer
   *
   * @param <Buffer> buffer - destination
   * @param <Number> pos - offset
   * @param <String> number - number to write
   * @return <Number> number of bytes written
   *
   * @api private
   */
  function writeNumberCached (stream, number) {
    debug('writeNumberCached: number: %d', number)
    debug('writeNumberCached: %o', numCache[number])
    return stream.write(numCache[number])
  }
  function writeNumberGenerated (stream, number) {
    const generatedNumber = generateNumber(number)
    debug('writeNumberGenerated: %o', generatedNumber)
    return stream.write(generatedNumber)
  }
  function write4ByteNumber (stream, number) {
    const generated4ByteBuffer = generate4ByteBuffer(number)
    debug('write4ByteNumber: %o', generated4ByteBuffer)
    return stream.write(generated4ByteBuffer)
  }
  /**
   * writeStringOrBuffer - write a String or Buffer with the its length prefix
   *
   * @param <Buffer> buffer - destination
   * @param <Number> pos - offset
   * @param <String> toWrite - String or Buffer
   * @return <Number> number of bytes written
   */
  function writeStringOrBuffer (stream, toWrite) {
    if (typeof toWrite === 'string') {
      writeString(stream, toWrite)
    } else if (toWrite) {
      writeNumber(stream, toWrite.length)
      stream.write(toWrite)
    } else writeNumber(stream, 0)
  }
  
  function getProperties (stream, properties) {
    /* connect properties */
    if (typeof properties !== 'object' || properties.length != null) {
      return {
        length: 1,
        write () {
          writeProperties(stream, {}, 0)
        }
      }
    }
    let propertiesLength = 0
    function getLengthProperty (name, value) {
      const type = protocol.propertiesTypes[name]
      let length = 0
      switch (type) {
        case 'byte': {
          if (typeof value !== 'boolean') {
            stream.emit('error', new Error(`Invalid ${name}: ${value}`))
            return false
          }
          length += 1 + 1
          break
        }
        case 'int8': {
          if (typeof value !== 'number' || value < 0 || value > 0xff) {
            stream.emit('error', new Error(`Invalid ${name}: ${value}`))
            return false
          }
          length += 1 + 1
          break
        }
        case 'binary': {
          if (value && value === null) {
            stream.emit('error', new Error(`Invalid ${name}: ${value}`))
            return false
          }
          length += 1 + Buffer.byteLength(value) + 2
          break
        }
        case 'int16': {
          if (typeof value !== 'number' || value < 0 || value > 0xffff) {
            stream.emit('error', new Error(`Invalid ${name}: ${value}`))
            return false
          }
          length += 1 + 2
          break
        }
        case 'int32': {
          if (typeof value !== 'number' || value < 0 || value > 0xffffffff) {
            stream.emit('error', new Error(`Invalid ${name}: ${value}`))
            return false
          }
          length += 1 + 4
          break
        }
        case 'var': {
          // var byte integer is max 24 bits packed in 32 bits
          if (typeof value !== 'number' || value < 0 || value > 0x0fffffff) {
            stream.emit('error', new Error(`Invalid ${name}: ${value}`))
            return false
          }
          length += 1 + Buffer.byteLength(genBufVariableByteInt(value))
          break
        }
        case 'string': {
          if (typeof value !== 'string') {
            stream.emit('error', new Error(`Invalid ${name}: ${value}`))
            return false
          }
          length += 1 + 2 + Buffer.byteLength(value.toString())
          break
        }
        case 'pair': {
          if (typeof value !== 'object') {
            stream.emit('error', new Error(`Invalid ${name}: ${value}`))
            return false
          }
          length += Object.getOwnPropertyNames(value).reduce((result, name) => {
            const currentValue = value[name]
            if (Array.isArray(currentValue)) {
              result += currentValue.reduce((currentLength, value) => {
                currentLength += 1 + 2 + Buffer.byteLength(name.toString()) + 2 + Buffer.byteLength(value.toString())
                return currentLength
              }, 0)
            } else {
              result += 1 + 2 + Buffer.byteLength(name.toString()) + 2 + Buffer.byteLength(value[name].toString())
            }
            return result
          }, 0)
          break
        }
        default: {
          stream.emit('error', new Error(`Invalid property ${name}: ${value}`))
          return false
        }
      }
      return length
    }
    if (properties) {
      for (const propName in properties) {
        let propLength = 0
        let propValueLength = 0
        const propValue = properties[propName]
        if (Array.isArray(propValue)) {
          for (let valueIndex = 0; valueIndex < propValue.length; valueIndex++) {
            propValueLength = getLengthProperty(propName, propValue[valueIndex])
            if (!propValueLength) { return false }
            propLength += propValueLength
          }
        } else {
          propValueLength = getLengthProperty(propName, propValue)
          if (!propValueLength) { return false }
          propLength = propValueLength
        }
        if (!propLength) return false
        propertiesLength += propLength
      }
    }
    const propertiesLengthLength = Buffer.byteLength(genBufVariableByteInt(propertiesLength))
  
    return {
      length: propertiesLengthLength + propertiesLength,
      write () {
        writeProperties(stream, properties, propertiesLength)
      }
    }
  }
  
  function getPropertiesByMaximumPacketSize (stream, properties, opts, length) {
    const mayEmptyProps = ['reasonString', 'userProperties']
    const maximumPacketSize = opts && opts.properties && opts.properties.maximumPacketSize ? opts.properties.maximumPacketSize : 0
  
    let propertiesData = getProperties(stream, properties)
    if (maximumPacketSize) {
      while (length + propertiesData.length > maximumPacketSize) {
        const currentMayEmptyProp = mayEmptyProps.shift()
        if (currentMayEmptyProp && properties[currentMayEmptyProp]) {
          delete properties[currentMayEmptyProp]
          propertiesData = getProperties(stream, properties)
        } else {
          return false
        }
      }
    }
    return propertiesData
  }
  
  function writeProperty (stream, propName, value) {
    const type = protocol.propertiesTypes[propName]
    switch (type) {
      case 'byte': {
        stream.write(Buffer.from([protocol.properties[propName]]))
        stream.write(Buffer.from([+value]))
        break
      }
      case 'int8': {
        stream.write(Buffer.from([protocol.properties[propName]]))
        stream.write(Buffer.from([value]))
        break
      }
      case 'binary': {
        stream.write(Buffer.from([protocol.properties[propName]]))
        writeStringOrBuffer(stream, value)
        break
      }
      case 'int16': {
        stream.write(Buffer.from([protocol.properties[propName]]))
        writeNumber(stream, value)
        break
      }
      case 'int32': {
        stream.write(Buffer.from([protocol.properties[propName]]))
        write4ByteNumber(stream, value)
        break
      }
      case 'var': {
        stream.write(Buffer.from([protocol.properties[propName]]))
        writeVarByteInt(stream, value)
        break
      }
      case 'string': {
        stream.write(Buffer.from([protocol.properties[propName]]))
        writeString(stream, value)
        break
      }
      case 'pair': {
        Object.getOwnPropertyNames(value).forEach(name => {
          const currentValue = value[name]
          if (Array.isArray(currentValue)) {
            currentValue.forEach(value => {
              stream.write(Buffer.from([protocol.properties[propName]]))
              writeStringPair(stream, name.toString(), value.toString())
            })
          } else {
            stream.write(Buffer.from([protocol.properties[propName]]))
            writeStringPair(stream, name.toString(), currentValue.toString())
          }
        })
        break
      }
      default: {
        stream.emit('error', new Error(`Invalid property ${propName} value: ${value}`))
        return false
      }
    }
  }
  
  function writeProperties (stream, properties, propertiesLength) {
    /* write properties to stream */
    writeVarByteInt(stream, propertiesLength)
    for (const propName in properties) {
      if (Object.prototype.hasOwnProperty.call(properties, propName) && properties[propName] !== null) {
        const value = properties[propName]
        if (Array.isArray(value)) {
          for (let valueIndex = 0; valueIndex < value.length; valueIndex++) {
            writeProperty(stream, propName, value[valueIndex])
          }
        } else {
          writeProperty(stream, propName, value)
        }
      }
    }
  }
  
  function byteLength (bufOrString) {
    if (!bufOrString) return 0
    else if (bufOrString instanceof Buffer) return bufOrString.length
    else return Buffer.byteLength(bufOrString)
  }
  
  function isStringOrBuffer (field) {
    return typeof field === 'string' || field instanceof Buffer
  }
  
  module.exports = generate
  
  }).call(this,require("buffer").Buffer)
  },{"./constants":32,"./numbers":37,"buffer":12,"debug":14,"process-nextick-args":43}],41:[function(require,module,exports){
  /**
   * Helpers.
   */
  
  var s = 1000;
  var m = s * 60;
  var h = m * 60;
  var d = h * 24;
  var w = d * 7;
  var y = d * 365.25;
  
  /**
   * Parse or format the given `val`.
   *
   * Options:
   *
   *  - `long` verbose formatting [false]
   *
   * @param {String|Number} val
   * @param {Object} [options]
   * @throws {Error} throw an error if val is not a non-empty string or a number
   * @return {String|Number}
   * @api public
   */
  
  module.exports = function(val, options) {
    options = options || {};
    var type = typeof val;
    if (type === 'string' && val.length > 0) {
      return parse(val);
    } else if (type === 'number' && isFinite(val)) {
      return options.long ? fmtLong(val) : fmtShort(val);
    }
    throw new Error(
      'val is not a non-empty string or a valid number. val=' +
        JSON.stringify(val)
    );
  };
  
  /**
   * Parse the given `str` and return milliseconds.
   *
   * @param {String} str
   * @return {Number}
   * @api private
   */
  
  function parse(str) {
    str = String(str);
    if (str.length > 100) {
      return;
    }
    var match = /^(-?(?:\d+)?\.?\d+) *(milliseconds?|msecs?|ms|seconds?|secs?|s|minutes?|mins?|m|hours?|hrs?|h|days?|d|weeks?|w|years?|yrs?|y)?$/i.exec(
      str
    );
    if (!match) {
      return;
    }
    var n = parseFloat(match[1]);
    var type = (match[2] || 'ms').toLowerCase();
    switch (type) {
      case 'years':
      case 'year':
      case 'yrs':
      case 'yr':
      case 'y':
        return n * y;
      case 'weeks':
      case 'week':
      case 'w':
        return n * w;
      case 'days':
      case 'day':
      case 'd':
        return n * d;
      case 'hours':
      case 'hour':
      case 'hrs':
      case 'hr':
      case 'h':
        return n * h;
      case 'minutes':
      case 'minute':
      case 'mins':
      case 'min':
      case 'm':
        return n * m;
      case 'seconds':
      case 'second':
      case 'secs':
      case 'sec':
      case 's':
        return n * s;
      case 'milliseconds':
      case 'millisecond':
      case 'msecs':
      case 'msec':
      case 'ms':
        return n;
      default:
        return undefined;
    }
  }
  
  /**
   * Short format for `ms`.
   *
   * @param {Number} ms
   * @return {String}
   * @api private
   */
  
  function fmtShort(ms) {
    var msAbs = Math.abs(ms);
    if (msAbs >= d) {
      return Math.round(ms / d) + 'd';
    }
    if (msAbs >= h) {
      return Math.round(ms / h) + 'h';
    }
    if (msAbs >= m) {
      return Math.round(ms / m) + 'm';
    }
    if (msAbs >= s) {
      return Math.round(ms / s) + 's';
    }
    return ms + 'ms';
  }
  
  /**
   * Long format for `ms`.
   *
   * @param {Number} ms
   * @return {String}
   * @api private
   */
  
  function fmtLong(ms) {
    var msAbs = Math.abs(ms);
    if (msAbs >= d) {
      return plural(ms, msAbs, d, 'day');
    }
    if (msAbs >= h) {
      return plural(ms, msAbs, h, 'hour');
    }
    if (msAbs >= m) {
      return plural(ms, msAbs, m, 'minute');
    }
    if (msAbs >= s) {
      return plural(ms, msAbs, s, 'second');
    }
    return ms + ' ms';
  }
  
  /**
   * Pluralization helper.
   */
  
  function plural(ms, msAbs, n, name) {
    var isPlural = msAbs >= n * 1.5;
    return Math.round(ms / n) + ' ' + name + (isPlural ? 's' : '');
  }
  
  },{}],42:[function(require,module,exports){
  var wrappy = require('wrappy')
  module.exports = wrappy(once)
  module.exports.strict = wrappy(onceStrict)
  
  once.proto = once(function () {
    Object.defineProperty(Function.prototype, 'once', {
      value: function () {
        return once(this)
      },
      configurable: true
    })
  
    Object.defineProperty(Function.prototype, 'onceStrict', {
      value: function () {
        return onceStrict(this)
      },
      configurable: true
    })
  })
  
  function once (fn) {
    var f = function () {
      if (f.called) return f.value
      f.called = true
      return f.value = fn.apply(this, arguments)
    }
    f.called = false
    return f
  }
  
  function onceStrict (fn) {
    var f = function () {
      if (f.called)
        throw new Error(f.onceError)
      f.called = true
      return f.value = fn.apply(this, arguments)
    }
    var name = fn.name || 'Function wrapped with `once`'
    f.onceError = name + " shouldn't be called more than once"
    f.called = false
    return f
  }
  
  },{"wrappy":66}],43:[function(require,module,exports){
  (function (process){
  'use strict';
  
  if (typeof process === 'undefined' ||
      !process.version ||
      process.version.indexOf('v0.') === 0 ||
      process.version.indexOf('v1.') === 0 && process.version.indexOf('v1.8.') !== 0) {
    module.exports = { nextTick: nextTick };
  } else {
    module.exports = process
  }
  
  function nextTick(fn, arg1, arg2, arg3) {
    if (typeof fn !== 'function') {
      throw new TypeError('"callback" argument must be a function');
    }
    var len = arguments.length;
    var args, i;
    switch (len) {
    case 0:
    case 1:
      return process.nextTick(fn);
    case 2:
      return process.nextTick(function afterTickOne() {
        fn.call(null, arg1);
      });
    case 3:
      return process.nextTick(function afterTickTwo() {
        fn.call(null, arg1, arg2);
      });
    case 4:
      return process.nextTick(function afterTickThree() {
        fn.call(null, arg1, arg2, arg3);
      });
    default:
      args = new Array(len - 1);
      i = 0;
      while (i < args.length) {
        args[i++] = arguments[i];
      }
      return process.nextTick(function afterTick() {
        fn.apply(null, args);
      });
    }
  }
  
  
  }).call(this,require('_process'))
  },{"_process":44}],44:[function(require,module,exports){
  // shim for using process in browser
  var process = module.exports = {};
  
  // cached from whatever global is present so that test runners that stub it
  // don't break things.  But we need to wrap it in a try catch in case it is
  // wrapped in strict mode code which doesn't define any globals.  It's inside a
  // function because try/catches deoptimize in certain engines.
  
  var cachedSetTimeout;
  var cachedClearTimeout;
  
  function defaultSetTimout() {
      throw new Error('setTimeout has not been defined');
  }
  function defaultClearTimeout () {
      throw new Error('clearTimeout has not been defined');
  }
  (function () {
      try {
          if (typeof setTimeout === 'function') {
              cachedSetTimeout = setTimeout;
          } else {
              cachedSetTimeout = defaultSetTimout;
          }
      } catch (e) {
          cachedSetTimeout = defaultSetTimout;
      }
      try {
          if (typeof clearTimeout === 'function') {
              cachedClearTimeout = clearTimeout;
          } else {
              cachedClearTimeout = defaultClearTimeout;
          }
      } catch (e) {
          cachedClearTimeout = defaultClearTimeout;
      }
  } ())
  function runTimeout(fun) {
      if (cachedSetTimeout === setTimeout) {
          //normal enviroments in sane situations
          return setTimeout(fun, 0);
      }
      // if setTimeout wasn't available but was latter defined
      if ((cachedSetTimeout === defaultSetTimout || !cachedSetTimeout) && setTimeout) {
          cachedSetTimeout = setTimeout;
          return setTimeout(fun, 0);
      }
      try {
          // when when somebody has screwed with setTimeout but no I.E. maddness
          return cachedSetTimeout(fun, 0);
      } catch(e){
          try {
              // When we are in I.E. but the script has been evaled so I.E. doesn't trust the global object when called normally
              return cachedSetTimeout.call(null, fun, 0);
          } catch(e){
              // same as above but when it's a version of I.E. that must have the global object for 'this', hopfully our context correct otherwise it will throw a global error
              return cachedSetTimeout.call(this, fun, 0);
          }
      }
  
  
  }
  function runClearTimeout(marker) {
      if (cachedClearTimeout === clearTimeout) {
          //normal enviroments in sane situations
          return clearTimeout(marker);
      }
      // if clearTimeout wasn't available but was latter defined
      if ((cachedClearTimeout === defaultClearTimeout || !cachedClearTimeout) && clearTimeout) {
          cachedClearTimeout = clearTimeout;
          return clearTimeout(marker);
      }
      try {
          // when when somebody has screwed with setTimeout but no I.E. maddness
          return cachedClearTimeout(marker);
      } catch (e){
          try {
              // When we are in I.E. but the script has been evaled so I.E. doesn't  trust the global object when called normally
              return cachedClearTimeout.call(null, marker);
          } catch (e){
              // same as above but when it's a version of I.E. that must have the global object for 'this', hopfully our context correct otherwise it will throw a global error.
              // Some versions of I.E. have different rules for clearTimeout vs setTimeout
              return cachedClearTimeout.call(this, marker);
          }
      }
  
  
  
  }
  var queue = [];
  var draining = false;
  var currentQueue;
  var queueIndex = -1;
  
  function cleanUpNextTick() {
      if (!draining || !currentQueue) {
          return;
      }
      draining = false;
      if (currentQueue.length) {
          queue = currentQueue.concat(queue);
      } else {
          queueIndex = -1;
      }
      if (queue.length) {
          drainQueue();
      }
  }
  
  function drainQueue() {
      if (draining) {
          return;
      }
      var timeout = runTimeout(cleanUpNextTick);
      draining = true;
  
      var len = queue.length;
      while(len) {
          currentQueue = queue;
          queue = [];
          while (++queueIndex < len) {
              if (currentQueue) {
                  currentQueue[queueIndex].run();
              }
          }
          queueIndex = -1;
          len = queue.length;
      }
      currentQueue = null;
      draining = false;
      runClearTimeout(timeout);
  }
  
  process.nextTick = function (fun) {
      var args = new Array(arguments.length - 1);
      if (arguments.length > 1) {
          for (var i = 1; i < arguments.length; i++) {
              args[i - 1] = arguments[i];
          }
      }
      queue.push(new Item(fun, args));
      if (queue.length === 1 && !draining) {
          runTimeout(drainQueue);
      }
  };
  
  // v8 likes predictible objects
  function Item(fun, array) {
      this.fun = fun;
      this.array = array;
  }
  Item.prototype.run = function () {
      this.fun.apply(null, this.array);
  };
  process.title = 'browser';
  process.browser = true;
  process.env = {};
  process.argv = [];
  process.version = ''; // empty string to avoid regexp issues
  process.versions = {};
  
  function noop() {}
  
  process.on = noop;
  process.addListener = noop;
  process.once = noop;
  process.off = noop;
  process.removeListener = noop;
  process.removeAllListeners = noop;
  process.emit = noop;
  process.prependListener = noop;
  process.prependOnceListener = noop;
  
  process.listeners = function (name) { return [] }
  
  process.binding = function (name) {
      throw new Error('process.binding is not supported');
  };
  
  process.cwd = function () { return '/' };
  process.chdir = function (dir) {
      throw new Error('process.chdir is not supported');
  };
  process.umask = function() { return 0; };
  
  },{}],45:[function(require,module,exports){
  'use strict';
  
  function _inheritsLoose(subClass, superClass) { subClass.prototype = Object.create(superClass.prototype); subClass.prototype.constructor = subClass; subClass.__proto__ = superClass; }
  
  var codes = {};
  
  function createErrorType(code, message, Base) {
    if (!Base) {
      Base = Error;
    }
  
    function getMessage(arg1, arg2, arg3) {
      if (typeof message === 'string') {
        return message;
      } else {
        return message(arg1, arg2, arg3);
      }
    }
  
    var NodeError =
    /*#__PURE__*/
    function (_Base) {
      _inheritsLoose(NodeError, _Base);
  
      function NodeError(arg1, arg2, arg3) {
        return _Base.call(this, getMessage(arg1, arg2, arg3)) || this;
      }
  
      return NodeError;
    }(Base);
  
    NodeError.prototype.name = Base.name;
    NodeError.prototype.code = code;
    codes[code] = NodeError;
  } // https://github.com/nodejs/node/blob/v10.8.0/lib/internal/errors.js
  
  
  function oneOf(expected, thing) {
    if (Array.isArray(expected)) {
      var len = expected.length;
      expected = expected.map(function (i) {
        return String(i);
      });
  
      if (len > 2) {
        return "one of ".concat(thing, " ").concat(expected.slice(0, len - 1).join(', '), ", or ") + expected[len - 1];
      } else if (len === 2) {
        return "one of ".concat(thing, " ").concat(expected[0], " or ").concat(expected[1]);
      } else {
        return "of ".concat(thing, " ").concat(expected[0]);
      }
    } else {
      return "of ".concat(thing, " ").concat(String(expected));
    }
  } // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/startsWith
  
  
  function startsWith(str, search, pos) {
    return str.substr(!pos || pos < 0 ? 0 : +pos, search.length) === search;
  } // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/endsWith
  
  
  function endsWith(str, search, this_len) {
    if (this_len === undefined || this_len > str.length) {
      this_len = str.length;
    }
  
    return str.substring(this_len - search.length, this_len) === search;
  } // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/includes
  
  
  function includes(str, search, start) {
    if (typeof start !== 'number') {
      start = 0;
    }
  
    if (start + search.length > str.length) {
      return false;
    } else {
      return str.indexOf(search, start) !== -1;
    }
  }
  
  createErrorType('ERR_INVALID_OPT_VALUE', function (name, value) {
    return 'The value "' + value + '" is invalid for option "' + name + '"';
  }, TypeError);
  createErrorType('ERR_INVALID_ARG_TYPE', function (name, expected, actual) {
    // determiner: 'must be' or 'must not be'
    var determiner;
  
    if (typeof expected === 'string' && startsWith(expected, 'not ')) {
      determiner = 'must not be';
      expected = expected.replace(/^not /, '');
    } else {
      determiner = 'must be';
    }
  
    var msg;
  
    if (endsWith(name, ' argument')) {
      // For cases like 'first argument'
      msg = "The ".concat(name, " ").concat(determiner, " ").concat(oneOf(expected, 'type'));
    } else {
      var type = includes(name, '.') ? 'property' : 'argument';
      msg = "The \"".concat(name, "\" ").concat(type, " ").concat(determiner, " ").concat(oneOf(expected, 'type'));
    }
  
    msg += ". Received type ".concat(typeof actual);
    return msg;
  }, TypeError);
  createErrorType('ERR_STREAM_PUSH_AFTER_EOF', 'stream.push() after EOF');
  createErrorType('ERR_METHOD_NOT_IMPLEMENTED', function (name) {
    return 'The ' + name + ' method is not implemented';
  });
  createErrorType('ERR_STREAM_PREMATURE_CLOSE', 'Premature close');
  createErrorType('ERR_STREAM_DESTROYED', function (name) {
    return 'Cannot call ' + name + ' after a stream was destroyed';
  });
  createErrorType('ERR_MULTIPLE_CALLBACK', 'Callback called multiple times');
  createErrorType('ERR_STREAM_CANNOT_PIPE', 'Cannot pipe, not readable');
  createErrorType('ERR_STREAM_WRITE_AFTER_END', 'write after end');
  createErrorType('ERR_STREAM_NULL_VALUES', 'May not write null values to stream', TypeError);
  createErrorType('ERR_UNKNOWN_ENCODING', function (arg) {
    return 'Unknown encoding: ' + arg;
  }, TypeError);
  createErrorType('ERR_STREAM_UNSHIFT_AFTER_END_EVENT', 'stream.unshift() after end event');
  module.exports.codes = codes;
  
  },{}],46:[function(require,module,exports){
  (function (process){
  // Copyright Joyent, Inc. and other Node contributors.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a
  // copy of this software and associated documentation files (the
  // "Software"), to deal in the Software without restriction, including
  // without limitation the rights to use, copy, modify, merge, publish,
  // distribute, sublicense, and/or sell copies of the Software, and to permit
  // persons to whom the Software is furnished to do so, subject to the
  // following conditions:
  //
  // The above copyright notice and this permission notice shall be included
  // in all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
  // NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
  // DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  // USE OR OTHER DEALINGS IN THE SOFTWARE.
  // a duplex stream is just a stream that is both readable and writable.
  // Since JS doesn't have multiple prototypal inheritance, this class
  // prototypally inherits from Readable, and then parasitically from
  // Writable.
  'use strict';
  /*<replacement>*/
  
  var objectKeys = Object.keys || function (obj) {
    var keys = [];
  
    for (var key in obj) {
      keys.push(key);
    }
  
    return keys;
  };
  /*</replacement>*/
  
  
  module.exports = Duplex;
  
  var Readable = require('./_stream_readable');
  
  var Writable = require('./_stream_writable');
  
  require('inherits')(Duplex, Readable);
  
  {
    // Allow the keys array to be GC'ed.
    var keys = objectKeys(Writable.prototype);
  
    for (var v = 0; v < keys.length; v++) {
      var method = keys[v];
      if (!Duplex.prototype[method]) Duplex.prototype[method] = Writable.prototype[method];
    }
  }
  
  function Duplex(options) {
    if (!(this instanceof Duplex)) return new Duplex(options);
    Readable.call(this, options);
    Writable.call(this, options);
    this.allowHalfOpen = true;
  
    if (options) {
      if (options.readable === false) this.readable = false;
      if (options.writable === false) this.writable = false;
  
      if (options.allowHalfOpen === false) {
        this.allowHalfOpen = false;
        this.once('end', onend);
      }
    }
  }
  
  Object.defineProperty(Duplex.prototype, 'writableHighWaterMark', {
    // making it explicit this property is not enumerable
    // because otherwise some prototype manipulation in
    // userland will fail
    enumerable: false,
    get: function get() {
      return this._writableState.highWaterMark;
    }
  });
  Object.defineProperty(Duplex.prototype, 'writableBuffer', {
    // making it explicit this property is not enumerable
    // because otherwise some prototype manipulation in
    // userland will fail
    enumerable: false,
    get: function get() {
      return this._writableState && this._writableState.getBuffer();
    }
  });
  Object.defineProperty(Duplex.prototype, 'writableLength', {
    // making it explicit this property is not enumerable
    // because otherwise some prototype manipulation in
    // userland will fail
    enumerable: false,
    get: function get() {
      return this._writableState.length;
    }
  }); // the no-half-open enforcer
  
  function onend() {
    // If the writable side ended, then we're ok.
    if (this._writableState.ended) return; // no more data can be written.
    // But allow more writes to happen in this tick.
  
    process.nextTick(onEndNT, this);
  }
  
  function onEndNT(self) {
    self.end();
  }
  
  Object.defineProperty(Duplex.prototype, 'destroyed', {
    // making it explicit this property is not enumerable
    // because otherwise some prototype manipulation in
    // userland will fail
    enumerable: false,
    get: function get() {
      if (this._readableState === undefined || this._writableState === undefined) {
        return false;
      }
  
      return this._readableState.destroyed && this._writableState.destroyed;
    },
    set: function set(value) {
      // we ignore the value if the stream
      // has not been initialized yet
      if (this._readableState === undefined || this._writableState === undefined) {
        return;
      } // backward compatibility, the user is explicitly
      // managing destroyed
  
  
      this._readableState.destroyed = value;
      this._writableState.destroyed = value;
    }
  });
  }).call(this,require('_process'))
  },{"./_stream_readable":48,"./_stream_writable":50,"_process":44,"inherits":29}],47:[function(require,module,exports){
  // Copyright Joyent, Inc. and other Node contributors.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a
  // copy of this software and associated documentation files (the
  // "Software"), to deal in the Software without restriction, including
  // without limitation the rights to use, copy, modify, merge, publish,
  // distribute, sublicense, and/or sell copies of the Software, and to permit
  // persons to whom the Software is furnished to do so, subject to the
  // following conditions:
  //
  // The above copyright notice and this permission notice shall be included
  // in all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
  // NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
  // DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  // USE OR OTHER DEALINGS IN THE SOFTWARE.
  // a passthrough stream.
  // basically just the most minimal sort of Transform stream.
  // Every written chunk gets output as-is.
  'use strict';
  
  module.exports = PassThrough;
  
  var Transform = require('./_stream_transform');
  
  require('inherits')(PassThrough, Transform);
  
  function PassThrough(options) {
    if (!(this instanceof PassThrough)) return new PassThrough(options);
    Transform.call(this, options);
  }
  
  PassThrough.prototype._transform = function (chunk, encoding, cb) {
    cb(null, chunk);
  };
  },{"./_stream_transform":49,"inherits":29}],48:[function(require,module,exports){
  (function (process,global){
  // Copyright Joyent, Inc. and other Node contributors.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a
  // copy of this software and associated documentation files (the
  // "Software"), to deal in the Software without restriction, including
  // without limitation the rights to use, copy, modify, merge, publish,
  // distribute, sublicense, and/or sell copies of the Software, and to permit
  // persons to whom the Software is furnished to do so, subject to the
  // following conditions:
  //
  // The above copyright notice and this permission notice shall be included
  // in all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
  // NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
  // DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  // USE OR OTHER DEALINGS IN THE SOFTWARE.
  'use strict';
  
  module.exports = Readable;
  /*<replacement>*/
  
  var Duplex;
  /*</replacement>*/
  
  Readable.ReadableState = ReadableState;
  /*<replacement>*/
  
  var EE = require('events').EventEmitter;
  
  var EElistenerCount = function EElistenerCount(emitter, type) {
    return emitter.listeners(type).length;
  };
  /*</replacement>*/
  
  /*<replacement>*/
  
  
  var Stream = require('./internal/streams/stream');
  /*</replacement>*/
  
  
  var Buffer = require('buffer').Buffer;
  
  var OurUint8Array = global.Uint8Array || function () {};
  
  function _uint8ArrayToBuffer(chunk) {
    return Buffer.from(chunk);
  }
  
  function _isUint8Array(obj) {
    return Buffer.isBuffer(obj) || obj instanceof OurUint8Array;
  }
  /*<replacement>*/
  
  
  var debugUtil = require('util');
  
  var debug;
  
  if (debugUtil && debugUtil.debuglog) {
    debug = debugUtil.debuglog('stream');
  } else {
    debug = function debug() {};
  }
  /*</replacement>*/
  
  
  var BufferList = require('./internal/streams/buffer_list');
  
  var destroyImpl = require('./internal/streams/destroy');
  
  var _require = require('./internal/streams/state'),
      getHighWaterMark = _require.getHighWaterMark;
  
  var _require$codes = require('../errors').codes,
      ERR_INVALID_ARG_TYPE = _require$codes.ERR_INVALID_ARG_TYPE,
      ERR_STREAM_PUSH_AFTER_EOF = _require$codes.ERR_STREAM_PUSH_AFTER_EOF,
      ERR_METHOD_NOT_IMPLEMENTED = _require$codes.ERR_METHOD_NOT_IMPLEMENTED,
      ERR_STREAM_UNSHIFT_AFTER_END_EVENT = _require$codes.ERR_STREAM_UNSHIFT_AFTER_END_EVENT; // Lazy loaded to improve the startup performance.
  
  
  var StringDecoder;
  var createReadableStreamAsyncIterator;
  var from;
  
  require('inherits')(Readable, Stream);
  
  var errorOrDestroy = destroyImpl.errorOrDestroy;
  var kProxyEvents = ['error', 'close', 'destroy', 'pause', 'resume'];
  
  function prependListener(emitter, event, fn) {
    // Sadly this is not cacheable as some libraries bundle their own
    // event emitter implementation with them.
    if (typeof emitter.prependListener === 'function') return emitter.prependListener(event, fn); // This is a hack to make sure that our error handler is attached before any
    // userland ones.  NEVER DO THIS. This is here only because this code needs
    // to continue to work with older versions of Node.js that do not include
    // the prependListener() method. The goal is to eventually remove this hack.
  
    if (!emitter._events || !emitter._events[event]) emitter.on(event, fn);else if (Array.isArray(emitter._events[event])) emitter._events[event].unshift(fn);else emitter._events[event] = [fn, emitter._events[event]];
  }
  
  function ReadableState(options, stream, isDuplex) {
    Duplex = Duplex || require('./_stream_duplex');
    options = options || {}; // Duplex streams are both readable and writable, but share
    // the same options object.
    // However, some cases require setting options to different
    // values for the readable and the writable sides of the duplex stream.
    // These options can be provided separately as readableXXX and writableXXX.
  
    if (typeof isDuplex !== 'boolean') isDuplex = stream instanceof Duplex; // object stream flag. Used to make read(n) ignore n and to
    // make all the buffer merging and length checks go away
  
    this.objectMode = !!options.objectMode;
    if (isDuplex) this.objectMode = this.objectMode || !!options.readableObjectMode; // the point at which it stops calling _read() to fill the buffer
    // Note: 0 is a valid value, means "don't call _read preemptively ever"
  
    this.highWaterMark = getHighWaterMark(this, options, 'readableHighWaterMark', isDuplex); // A linked list is used to store data chunks instead of an array because the
    // linked list can remove elements from the beginning faster than
    // array.shift()
  
    this.buffer = new BufferList();
    this.length = 0;
    this.pipes = null;
    this.pipesCount = 0;
    this.flowing = null;
    this.ended = false;
    this.endEmitted = false;
    this.reading = false; // a flag to be able to tell if the event 'readable'/'data' is emitted
    // immediately, or on a later tick.  We set this to true at first, because
    // any actions that shouldn't happen until "later" should generally also
    // not happen before the first read call.
  
    this.sync = true; // whenever we return null, then we set a flag to say
    // that we're awaiting a 'readable' event emission.
  
    this.needReadable = false;
    this.emittedReadable = false;
    this.readableListening = false;
    this.resumeScheduled = false;
    this.paused = true; // Should close be emitted on destroy. Defaults to true.
  
    this.emitClose = options.emitClose !== false; // Should .destroy() be called after 'end' (and potentially 'finish')
  
    this.autoDestroy = !!options.autoDestroy; // has it been destroyed
  
    this.destroyed = false; // Crypto is kind of old and crusty.  Historically, its default string
    // encoding is 'binary' so we have to make this configurable.
    // Everything else in the universe uses 'utf8', though.
  
    this.defaultEncoding = options.defaultEncoding || 'utf8'; // the number of writers that are awaiting a drain event in .pipe()s
  
    this.awaitDrain = 0; // if true, a maybeReadMore has been scheduled
  
    this.readingMore = false;
    this.decoder = null;
    this.encoding = null;
  
    if (options.encoding) {
      if (!StringDecoder) StringDecoder = require('string_decoder/').StringDecoder;
      this.decoder = new StringDecoder(options.encoding);
      this.encoding = options.encoding;
    }
  }
  
  function Readable(options) {
    Duplex = Duplex || require('./_stream_duplex');
    if (!(this instanceof Readable)) return new Readable(options); // Checking for a Stream.Duplex instance is faster here instead of inside
    // the ReadableState constructor, at least with V8 6.5
  
    var isDuplex = this instanceof Duplex;
    this._readableState = new ReadableState(options, this, isDuplex); // legacy
  
    this.readable = true;
  
    if (options) {
      if (typeof options.read === 'function') this._read = options.read;
      if (typeof options.destroy === 'function') this._destroy = options.destroy;
    }
  
    Stream.call(this);
  }
  
  Object.defineProperty(Readable.prototype, 'destroyed', {
    // making it explicit this property is not enumerable
    // because otherwise some prototype manipulation in
    // userland will fail
    enumerable: false,
    get: function get() {
      if (this._readableState === undefined) {
        return false;
      }
  
      return this._readableState.destroyed;
    },
    set: function set(value) {
      // we ignore the value if the stream
      // has not been initialized yet
      if (!this._readableState) {
        return;
      } // backward compatibility, the user is explicitly
      // managing destroyed
  
  
      this._readableState.destroyed = value;
    }
  });
  Readable.prototype.destroy = destroyImpl.destroy;
  Readable.prototype._undestroy = destroyImpl.undestroy;
  
  Readable.prototype._destroy = function (err, cb) {
    cb(err);
  }; // Manually shove something into the read() buffer.
  // This returns true if the highWaterMark has not been hit yet,
  // similar to how Writable.write() returns true if you should
  // write() some more.
  
  
  Readable.prototype.push = function (chunk, encoding) {
    var state = this._readableState;
    var skipChunkCheck;
  
    if (!state.objectMode) {
      if (typeof chunk === 'string') {
        encoding = encoding || state.defaultEncoding;
  
        if (encoding !== state.encoding) {
          chunk = Buffer.from(chunk, encoding);
          encoding = '';
        }
  
        skipChunkCheck = true;
      }
    } else {
      skipChunkCheck = true;
    }
  
    return readableAddChunk(this, chunk, encoding, false, skipChunkCheck);
  }; // Unshift should *always* be something directly out of read()
  
  
  Readable.prototype.unshift = function (chunk) {
    return readableAddChunk(this, chunk, null, true, false);
  };
  
  function readableAddChunk(stream, chunk, encoding, addToFront, skipChunkCheck) {
    debug('readableAddChunk', chunk);
    var state = stream._readableState;
  
    if (chunk === null) {
      state.reading = false;
      onEofChunk(stream, state);
    } else {
      var er;
      if (!skipChunkCheck) er = chunkInvalid(state, chunk);
  
      if (er) {
        errorOrDestroy(stream, er);
      } else if (state.objectMode || chunk && chunk.length > 0) {
        if (typeof chunk !== 'string' && !state.objectMode && Object.getPrototypeOf(chunk) !== Buffer.prototype) {
          chunk = _uint8ArrayToBuffer(chunk);
        }
  
        if (addToFront) {
          if (state.endEmitted) errorOrDestroy(stream, new ERR_STREAM_UNSHIFT_AFTER_END_EVENT());else addChunk(stream, state, chunk, true);
        } else if (state.ended) {
          errorOrDestroy(stream, new ERR_STREAM_PUSH_AFTER_EOF());
        } else if (state.destroyed) {
          return false;
        } else {
          state.reading = false;
  
          if (state.decoder && !encoding) {
            chunk = state.decoder.write(chunk);
            if (state.objectMode || chunk.length !== 0) addChunk(stream, state, chunk, false);else maybeReadMore(stream, state);
          } else {
            addChunk(stream, state, chunk, false);
          }
        }
      } else if (!addToFront) {
        state.reading = false;
        maybeReadMore(stream, state);
      }
    } // We can push more data if we are below the highWaterMark.
    // Also, if we have no data yet, we can stand some more bytes.
    // This is to work around cases where hwm=0, such as the repl.
  
  
    return !state.ended && (state.length < state.highWaterMark || state.length === 0);
  }
  
  function addChunk(stream, state, chunk, addToFront) {
    if (state.flowing && state.length === 0 && !state.sync) {
      state.awaitDrain = 0;
      stream.emit('data', chunk);
    } else {
      // update the buffer info.
      state.length += state.objectMode ? 1 : chunk.length;
      if (addToFront) state.buffer.unshift(chunk);else state.buffer.push(chunk);
      if (state.needReadable) emitReadable(stream);
    }
  
    maybeReadMore(stream, state);
  }
  
  function chunkInvalid(state, chunk) {
    var er;
  
    if (!_isUint8Array(chunk) && typeof chunk !== 'string' && chunk !== undefined && !state.objectMode) {
      er = new ERR_INVALID_ARG_TYPE('chunk', ['string', 'Buffer', 'Uint8Array'], chunk);
    }
  
    return er;
  }
  
  Readable.prototype.isPaused = function () {
    return this._readableState.flowing === false;
  }; // backwards compatibility.
  
  
  Readable.prototype.setEncoding = function (enc) {
    if (!StringDecoder) StringDecoder = require('string_decoder/').StringDecoder;
    var decoder = new StringDecoder(enc);
    this._readableState.decoder = decoder; // If setEncoding(null), decoder.encoding equals utf8
  
    this._readableState.encoding = this._readableState.decoder.encoding; // Iterate over current buffer to convert already stored Buffers:
  
    var p = this._readableState.buffer.head;
    var content = '';
  
    while (p !== null) {
      content += decoder.write(p.data);
      p = p.next;
    }
  
    this._readableState.buffer.clear();
  
    if (content !== '') this._readableState.buffer.push(content);
    this._readableState.length = content.length;
    return this;
  }; // Don't raise the hwm > 1GB
  
  
  var MAX_HWM = 0x40000000;
  
  function computeNewHighWaterMark(n) {
    if (n >= MAX_HWM) {
      // TODO(ronag): Throw ERR_VALUE_OUT_OF_RANGE.
      n = MAX_HWM;
    } else {
      // Get the next highest power of 2 to prevent increasing hwm excessively in
      // tiny amounts
      n--;
      n |= n >>> 1;
      n |= n >>> 2;
      n |= n >>> 4;
      n |= n >>> 8;
      n |= n >>> 16;
      n++;
    }
  
    return n;
  } // This function is designed to be inlinable, so please take care when making
  // changes to the function body.
  
  
  function howMuchToRead(n, state) {
    if (n <= 0 || state.length === 0 && state.ended) return 0;
    if (state.objectMode) return 1;
  
    if (n !== n) {
      // Only flow one buffer at a time
      if (state.flowing && state.length) return state.buffer.head.data.length;else return state.length;
    } // If we're asking for more than the current hwm, then raise the hwm.
  
  
    if (n > state.highWaterMark) state.highWaterMark = computeNewHighWaterMark(n);
    if (n <= state.length) return n; // Don't have enough
  
    if (!state.ended) {
      state.needReadable = true;
      return 0;
    }
  
    return state.length;
  } // you can override either this method, or the async _read(n) below.
  
  
  Readable.prototype.read = function (n) {
    debug('read', n);
    n = parseInt(n, 10);
    var state = this._readableState;
    var nOrig = n;
    if (n !== 0) state.emittedReadable = false; // if we're doing read(0) to trigger a readable event, but we
    // already have a bunch of data in the buffer, then just trigger
    // the 'readable' event and move on.
  
    if (n === 0 && state.needReadable && ((state.highWaterMark !== 0 ? state.length >= state.highWaterMark : state.length > 0) || state.ended)) {
      debug('read: emitReadable', state.length, state.ended);
      if (state.length === 0 && state.ended) endReadable(this);else emitReadable(this);
      return null;
    }
  
    n = howMuchToRead(n, state); // if we've ended, and we're now clear, then finish it up.
  
    if (n === 0 && state.ended) {
      if (state.length === 0) endReadable(this);
      return null;
    } // All the actual chunk generation logic needs to be
    // *below* the call to _read.  The reason is that in certain
    // synthetic stream cases, such as passthrough streams, _read
    // may be a completely synchronous operation which may change
    // the state of the read buffer, providing enough data when
    // before there was *not* enough.
    //
    // So, the steps are:
    // 1. Figure out what the state of things will be after we do
    // a read from the buffer.
    //
    // 2. If that resulting state will trigger a _read, then call _read.
    // Note that this may be asynchronous, or synchronous.  Yes, it is
    // deeply ugly to write APIs this way, but that still doesn't mean
    // that the Readable class should behave improperly, as streams are
    // designed to be sync/async agnostic.
    // Take note if the _read call is sync or async (ie, if the read call
    // has returned yet), so that we know whether or not it's safe to emit
    // 'readable' etc.
    //
    // 3. Actually pull the requested chunks out of the buffer and return.
    // if we need a readable event, then we need to do some reading.
  
  
    var doRead = state.needReadable;
    debug('need readable', doRead); // if we currently have less than the highWaterMark, then also read some
  
    if (state.length === 0 || state.length - n < state.highWaterMark) {
      doRead = true;
      debug('length less than watermark', doRead);
    } // however, if we've ended, then there's no point, and if we're already
    // reading, then it's unnecessary.
  
  
    if (state.ended || state.reading) {
      doRead = false;
      debug('reading or ended', doRead);
    } else if (doRead) {
      debug('do read');
      state.reading = true;
      state.sync = true; // if the length is currently zero, then we *need* a readable event.
  
      if (state.length === 0) state.needReadable = true; // call internal read method
  
      this._read(state.highWaterMark);
  
      state.sync = false; // If _read pushed data synchronously, then `reading` will be false,
      // and we need to re-evaluate how much data we can return to the user.
  
      if (!state.reading) n = howMuchToRead(nOrig, state);
    }
  
    var ret;
    if (n > 0) ret = fromList(n, state);else ret = null;
  
    if (ret === null) {
      state.needReadable = state.length <= state.highWaterMark;
      n = 0;
    } else {
      state.length -= n;
      state.awaitDrain = 0;
    }
  
    if (state.length === 0) {
      // If we have nothing in the buffer, then we want to know
      // as soon as we *do* get something into the buffer.
      if (!state.ended) state.needReadable = true; // If we tried to read() past the EOF, then emit end on the next tick.
  
      if (nOrig !== n && state.ended) endReadable(this);
    }
  
    if (ret !== null) this.emit('data', ret);
    return ret;
  };
  
  function onEofChunk(stream, state) {
    debug('onEofChunk');
    if (state.ended) return;
  
    if (state.decoder) {
      var chunk = state.decoder.end();
  
      if (chunk && chunk.length) {
        state.buffer.push(chunk);
        state.length += state.objectMode ? 1 : chunk.length;
      }
    }
  
    state.ended = true;
  
    if (state.sync) {
      // if we are sync, wait until next tick to emit the data.
      // Otherwise we risk emitting data in the flow()
      // the readable code triggers during a read() call
      emitReadable(stream);
    } else {
      // emit 'readable' now to make sure it gets picked up.
      state.needReadable = false;
  
      if (!state.emittedReadable) {
        state.emittedReadable = true;
        emitReadable_(stream);
      }
    }
  } // Don't emit readable right away in sync mode, because this can trigger
  // another read() call => stack overflow.  This way, it might trigger
  // a nextTick recursion warning, but that's not so bad.
  
  
  function emitReadable(stream) {
    var state = stream._readableState;
    debug('emitReadable', state.needReadable, state.emittedReadable);
    state.needReadable = false;
  
    if (!state.emittedReadable) {
      debug('emitReadable', state.flowing);
      state.emittedReadable = true;
      process.nextTick(emitReadable_, stream);
    }
  }
  
  function emitReadable_(stream) {
    var state = stream._readableState;
    debug('emitReadable_', state.destroyed, state.length, state.ended);
  
    if (!state.destroyed && (state.length || state.ended)) {
      stream.emit('readable');
      state.emittedReadable = false;
    } // The stream needs another readable event if
    // 1. It is not flowing, as the flow mechanism will take
    //    care of it.
    // 2. It is not ended.
    // 3. It is below the highWaterMark, so we can schedule
    //    another readable later.
  
  
    state.needReadable = !state.flowing && !state.ended && state.length <= state.highWaterMark;
    flow(stream);
  } // at this point, the user has presumably seen the 'readable' event,
  // and called read() to consume some data.  that may have triggered
  // in turn another _read(n) call, in which case reading = true if
  // it's in progress.
  // However, if we're not ended, or reading, and the length < hwm,
  // then go ahead and try to read some more preemptively.
  
  
  function maybeReadMore(stream, state) {
    if (!state.readingMore) {
      state.readingMore = true;
      process.nextTick(maybeReadMore_, stream, state);
    }
  }
  
  function maybeReadMore_(stream, state) {
    // Attempt to read more data if we should.
    //
    // The conditions for reading more data are (one of):
    // - Not enough data buffered (state.length < state.highWaterMark). The loop
    //   is responsible for filling the buffer with enough data if such data
    //   is available. If highWaterMark is 0 and we are not in the flowing mode
    //   we should _not_ attempt to buffer any extra data. We'll get more data
    //   when the stream consumer calls read() instead.
    // - No data in the buffer, and the stream is in flowing mode. In this mode
    //   the loop below is responsible for ensuring read() is called. Failing to
    //   call read here would abort the flow and there's no other mechanism for
    //   continuing the flow if the stream consumer has just subscribed to the
    //   'data' event.
    //
    // In addition to the above conditions to keep reading data, the following
    // conditions prevent the data from being read:
    // - The stream has ended (state.ended).
    // - There is already a pending 'read' operation (state.reading). This is a
    //   case where the the stream has called the implementation defined _read()
    //   method, but they are processing the call asynchronously and have _not_
    //   called push() with new data. In this case we skip performing more
    //   read()s. The execution ends in this method again after the _read() ends
    //   up calling push() with more data.
    while (!state.reading && !state.ended && (state.length < state.highWaterMark || state.flowing && state.length === 0)) {
      var len = state.length;
      debug('maybeReadMore read 0');
      stream.read(0);
      if (len === state.length) // didn't get any data, stop spinning.
        break;
    }
  
    state.readingMore = false;
  } // abstract method.  to be overridden in specific implementation classes.
  // call cb(er, data) where data is <= n in length.
  // for virtual (non-string, non-buffer) streams, "length" is somewhat
  // arbitrary, and perhaps not very meaningful.
  
  
  Readable.prototype._read = function (n) {
    errorOrDestroy(this, new ERR_METHOD_NOT_IMPLEMENTED('_read()'));
  };
  
  Readable.prototype.pipe = function (dest, pipeOpts) {
    var src = this;
    var state = this._readableState;
  
    switch (state.pipesCount) {
      case 0:
        state.pipes = dest;
        break;
  
      case 1:
        state.pipes = [state.pipes, dest];
        break;
  
      default:
        state.pipes.push(dest);
        break;
    }
  
    state.pipesCount += 1;
    debug('pipe count=%d opts=%j', state.pipesCount, pipeOpts);
    var doEnd = (!pipeOpts || pipeOpts.end !== false) && dest !== process.stdout && dest !== process.stderr;
    var endFn = doEnd ? onend : unpipe;
    if (state.endEmitted) process.nextTick(endFn);else src.once('end', endFn);
    dest.on('unpipe', onunpipe);
  
    function onunpipe(readable, unpipeInfo) {
      debug('onunpipe');
  
      if (readable === src) {
        if (unpipeInfo && unpipeInfo.hasUnpiped === false) {
          unpipeInfo.hasUnpiped = true;
          cleanup();
        }
      }
    }
  
    function onend() {
      debug('onend');
      dest.end();
    } // when the dest drains, it reduces the awaitDrain counter
    // on the source.  This would be more elegant with a .once()
    // handler in flow(), but adding and removing repeatedly is
    // too slow.
  
  
    var ondrain = pipeOnDrain(src);
    dest.on('drain', ondrain);
    var cleanedUp = false;
  
    function cleanup() {
      debug('cleanup'); // cleanup event handlers once the pipe is broken
  
      dest.removeListener('close', onclose);
      dest.removeListener('finish', onfinish);
      dest.removeListener('drain', ondrain);
      dest.removeListener('error', onerror);
      dest.removeListener('unpipe', onunpipe);
      src.removeListener('end', onend);
      src.removeListener('end', unpipe);
      src.removeListener('data', ondata);
      cleanedUp = true; // if the reader is waiting for a drain event from this
      // specific writer, then it would cause it to never start
      // flowing again.
      // So, if this is awaiting a drain, then we just call it now.
      // If we don't know, then assume that we are waiting for one.
  
      if (state.awaitDrain && (!dest._writableState || dest._writableState.needDrain)) ondrain();
    }
  
    src.on('data', ondata);
  
    function ondata(chunk) {
      debug('ondata');
      var ret = dest.write(chunk);
      debug('dest.write', ret);
  
      if (ret === false) {
        // If the user unpiped during `dest.write()`, it is possible
        // to get stuck in a permanently paused state if that write
        // also returned false.
        // => Check whether `dest` is still a piping destination.
        if ((state.pipesCount === 1 && state.pipes === dest || state.pipesCount > 1 && indexOf(state.pipes, dest) !== -1) && !cleanedUp) {
          debug('false write response, pause', state.awaitDrain);
          state.awaitDrain++;
        }
  
        src.pause();
      }
    } // if the dest has an error, then stop piping into it.
    // however, don't suppress the throwing behavior for this.
  
  
    function onerror(er) {
      debug('onerror', er);
      unpipe();
      dest.removeListener('error', onerror);
      if (EElistenerCount(dest, 'error') === 0) errorOrDestroy(dest, er);
    } // Make sure our error handler is attached before userland ones.
  
  
    prependListener(dest, 'error', onerror); // Both close and finish should trigger unpipe, but only once.
  
    function onclose() {
      dest.removeListener('finish', onfinish);
      unpipe();
    }
  
    dest.once('close', onclose);
  
    function onfinish() {
      debug('onfinish');
      dest.removeListener('close', onclose);
      unpipe();
    }
  
    dest.once('finish', onfinish);
  
    function unpipe() {
      debug('unpipe');
      src.unpipe(dest);
    } // tell the dest that it's being piped to
  
  
    dest.emit('pipe', src); // start the flow if it hasn't been started already.
  
    if (!state.flowing) {
      debug('pipe resume');
      src.resume();
    }
  
    return dest;
  };
  
  function pipeOnDrain(src) {
    return function pipeOnDrainFunctionResult() {
      var state = src._readableState;
      debug('pipeOnDrain', state.awaitDrain);
      if (state.awaitDrain) state.awaitDrain--;
  
      if (state.awaitDrain === 0 && EElistenerCount(src, 'data')) {
        state.flowing = true;
        flow(src);
      }
    };
  }
  
  Readable.prototype.unpipe = function (dest) {
    var state = this._readableState;
    var unpipeInfo = {
      hasUnpiped: false
    }; // if we're not piping anywhere, then do nothing.
  
    if (state.pipesCount === 0) return this; // just one destination.  most common case.
  
    if (state.pipesCount === 1) {
      // passed in one, but it's not the right one.
      if (dest && dest !== state.pipes) return this;
      if (!dest) dest = state.pipes; // got a match.
  
      state.pipes = null;
      state.pipesCount = 0;
      state.flowing = false;
      if (dest) dest.emit('unpipe', this, unpipeInfo);
      return this;
    } // slow case. multiple pipe destinations.
  
  
    if (!dest) {
      // remove all.
      var dests = state.pipes;
      var len = state.pipesCount;
      state.pipes = null;
      state.pipesCount = 0;
      state.flowing = false;
  
      for (var i = 0; i < len; i++) {
        dests[i].emit('unpipe', this, {
          hasUnpiped: false
        });
      }
  
      return this;
    } // try to find the right one.
  
  
    var index = indexOf(state.pipes, dest);
    if (index === -1) return this;
    state.pipes.splice(index, 1);
    state.pipesCount -= 1;
    if (state.pipesCount === 1) state.pipes = state.pipes[0];
    dest.emit('unpipe', this, unpipeInfo);
    return this;
  }; // set up data events if they are asked for
  // Ensure readable listeners eventually get something
  
  
  Readable.prototype.on = function (ev, fn) {
    var res = Stream.prototype.on.call(this, ev, fn);
    var state = this._readableState;
  
    if (ev === 'data') {
      // update readableListening so that resume() may be a no-op
      // a few lines down. This is needed to support once('readable').
      state.readableListening = this.listenerCount('readable') > 0; // Try start flowing on next tick if stream isn't explicitly paused
  
      if (state.flowing !== false) this.resume();
    } else if (ev === 'readable') {
      if (!state.endEmitted && !state.readableListening) {
        state.readableListening = state.needReadable = true;
        state.flowing = false;
        state.emittedReadable = false;
        debug('on readable', state.length, state.reading);
  
        if (state.length) {
          emitReadable(this);
        } else if (!state.reading) {
          process.nextTick(nReadingNextTick, this);
        }
      }
    }
  
    return res;
  };
  
  Readable.prototype.addListener = Readable.prototype.on;
  
  Readable.prototype.removeListener = function (ev, fn) {
    var res = Stream.prototype.removeListener.call(this, ev, fn);
  
    if (ev === 'readable') {
      // We need to check if there is someone still listening to
      // readable and reset the state. However this needs to happen
      // after readable has been emitted but before I/O (nextTick) to
      // support once('readable', fn) cycles. This means that calling
      // resume within the same tick will have no
      // effect.
      process.nextTick(updateReadableListening, this);
    }
  
    return res;
  };
  
  Readable.prototype.removeAllListeners = function (ev) {
    var res = Stream.prototype.removeAllListeners.apply(this, arguments);
  
    if (ev === 'readable' || ev === undefined) {
      // We need to check if there is someone still listening to
      // readable and reset the state. However this needs to happen
      // after readable has been emitted but before I/O (nextTick) to
      // support once('readable', fn) cycles. This means that calling
      // resume within the same tick will have no
      // effect.
      process.nextTick(updateReadableListening, this);
    }
  
    return res;
  };
  
  function updateReadableListening(self) {
    var state = self._readableState;
    state.readableListening = self.listenerCount('readable') > 0;
  
    if (state.resumeScheduled && !state.paused) {
      // flowing needs to be set to true now, otherwise
      // the upcoming resume will not flow.
      state.flowing = true; // crude way to check if we should resume
    } else if (self.listenerCount('data') > 0) {
      self.resume();
    }
  }
  
  function nReadingNextTick(self) {
    debug('readable nexttick read 0');
    self.read(0);
  } // pause() and resume() are remnants of the legacy readable stream API
  // If the user uses them, then switch into old mode.
  
  
  Readable.prototype.resume = function () {
    var state = this._readableState;
  
    if (!state.flowing) {
      debug('resume'); // we flow only if there is no one listening
      // for readable, but we still have to call
      // resume()
  
      state.flowing = !state.readableListening;
      resume(this, state);
    }
  
    state.paused = false;
    return this;
  };
  
  function resume(stream, state) {
    if (!state.resumeScheduled) {
      state.resumeScheduled = true;
      process.nextTick(resume_, stream, state);
    }
  }
  
  function resume_(stream, state) {
    debug('resume', state.reading);
  
    if (!state.reading) {
      stream.read(0);
    }
  
    state.resumeScheduled = false;
    stream.emit('resume');
    flow(stream);
    if (state.flowing && !state.reading) stream.read(0);
  }
  
  Readable.prototype.pause = function () {
    debug('call pause flowing=%j', this._readableState.flowing);
  
    if (this._readableState.flowing !== false) {
      debug('pause');
      this._readableState.flowing = false;
      this.emit('pause');
    }
  
    this._readableState.paused = true;
    return this;
  };
  
  function flow(stream) {
    var state = stream._readableState;
    debug('flow', state.flowing);
  
    while (state.flowing && stream.read() !== null) {
      ;
    }
  } // wrap an old-style stream as the async data source.
  // This is *not* part of the readable stream interface.
  // It is an ugly unfortunate mess of history.
  
  
  Readable.prototype.wrap = function (stream) {
    var _this = this;
  
    var state = this._readableState;
    var paused = false;
    stream.on('end', function () {
      debug('wrapped end');
  
      if (state.decoder && !state.ended) {
        var chunk = state.decoder.end();
        if (chunk && chunk.length) _this.push(chunk);
      }
  
      _this.push(null);
    });
    stream.on('data', function (chunk) {
      debug('wrapped data');
      if (state.decoder) chunk = state.decoder.write(chunk); // don't skip over falsy values in objectMode
  
      if (state.objectMode && (chunk === null || chunk === undefined)) return;else if (!state.objectMode && (!chunk || !chunk.length)) return;
  
      var ret = _this.push(chunk);
  
      if (!ret) {
        paused = true;
        stream.pause();
      }
    }); // proxy all the other methods.
    // important when wrapping filters and duplexes.
  
    for (var i in stream) {
      if (this[i] === undefined && typeof stream[i] === 'function') {
        this[i] = function methodWrap(method) {
          return function methodWrapReturnFunction() {
            return stream[method].apply(stream, arguments);
          };
        }(i);
      }
    } // proxy certain important events.
  
  
    for (var n = 0; n < kProxyEvents.length; n++) {
      stream.on(kProxyEvents[n], this.emit.bind(this, kProxyEvents[n]));
    } // when we try to consume some more bytes, simply unpause the
    // underlying stream.
  
  
    this._read = function (n) {
      debug('wrapped _read', n);
  
      if (paused) {
        paused = false;
        stream.resume();
      }
    };
  
    return this;
  };
  
  if (typeof Symbol === 'function') {
    Readable.prototype[Symbol.asyncIterator] = function () {
      if (createReadableStreamAsyncIterator === undefined) {
        createReadableStreamAsyncIterator = require('./internal/streams/async_iterator');
      }
  
      return createReadableStreamAsyncIterator(this);
    };
  }
  
  Object.defineProperty(Readable.prototype, 'readableHighWaterMark', {
    // making it explicit this property is not enumerable
    // because otherwise some prototype manipulation in
    // userland will fail
    enumerable: false,
    get: function get() {
      return this._readableState.highWaterMark;
    }
  });
  Object.defineProperty(Readable.prototype, 'readableBuffer', {
    // making it explicit this property is not enumerable
    // because otherwise some prototype manipulation in
    // userland will fail
    enumerable: false,
    get: function get() {
      return this._readableState && this._readableState.buffer;
    }
  });
  Object.defineProperty(Readable.prototype, 'readableFlowing', {
    // making it explicit this property is not enumerable
    // because otherwise some prototype manipulation in
    // userland will fail
    enumerable: false,
    get: function get() {
      return this._readableState.flowing;
    },
    set: function set(state) {
      if (this._readableState) {
        this._readableState.flowing = state;
      }
    }
  }); // exposed for testing purposes only.
  
  Readable._fromList = fromList;
  Object.defineProperty(Readable.prototype, 'readableLength', {
    // making it explicit this property is not enumerable
    // because otherwise some prototype manipulation in
    // userland will fail
    enumerable: false,
    get: function get() {
      return this._readableState.length;
    }
  }); // Pluck off n bytes from an array of buffers.
  // Length is the combined lengths of all the buffers in the list.
  // This function is designed to be inlinable, so please take care when making
  // changes to the function body.
  
  function fromList(n, state) {
    // nothing buffered
    if (state.length === 0) return null;
    var ret;
    if (state.objectMode) ret = state.buffer.shift();else if (!n || n >= state.length) {
      // read it all, truncate the list
      if (state.decoder) ret = state.buffer.join('');else if (state.buffer.length === 1) ret = state.buffer.first();else ret = state.buffer.concat(state.length);
      state.buffer.clear();
    } else {
      // read part of list
      ret = state.buffer.consume(n, state.decoder);
    }
    return ret;
  }
  
  function endReadable(stream) {
    var state = stream._readableState;
    debug('endReadable', state.endEmitted);
  
    if (!state.endEmitted) {
      state.ended = true;
      process.nextTick(endReadableNT, state, stream);
    }
  }
  
  function endReadableNT(state, stream) {
    debug('endReadableNT', state.endEmitted, state.length); // Check that we didn't get one last unshift.
  
    if (!state.endEmitted && state.length === 0) {
      state.endEmitted = true;
      stream.readable = false;
      stream.emit('end');
  
      if (state.autoDestroy) {
        // In case of duplex streams we need a way to detect
        // if the writable side is ready for autoDestroy as well
        var wState = stream._writableState;
  
        if (!wState || wState.autoDestroy && wState.finished) {
          stream.destroy();
        }
      }
    }
  }
  
  if (typeof Symbol === 'function') {
    Readable.from = function (iterable, opts) {
      if (from === undefined) {
        from = require('./internal/streams/from');
      }
  
      return from(Readable, iterable, opts);
    };
  }
  
  function indexOf(xs, x) {
    for (var i = 0, l = xs.length; i < l; i++) {
      if (xs[i] === x) return i;
    }
  
    return -1;
  }
  }).call(this,require('_process'),typeof global !== "undefined" ? global : typeof self !== "undefined" ? self : typeof window !== "undefined" ? window : {})
  },{"../errors":45,"./_stream_duplex":46,"./internal/streams/async_iterator":51,"./internal/streams/buffer_list":52,"./internal/streams/destroy":53,"./internal/streams/from":55,"./internal/streams/state":57,"./internal/streams/stream":58,"_process":44,"buffer":12,"events":27,"inherits":29,"string_decoder/":63,"util":11}],49:[function(require,module,exports){
  // Copyright Joyent, Inc. and other Node contributors.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a
  // copy of this software and associated documentation files (the
  // "Software"), to deal in the Software without restriction, including
  // without limitation the rights to use, copy, modify, merge, publish,
  // distribute, sublicense, and/or sell copies of the Software, and to permit
  // persons to whom the Software is furnished to do so, subject to the
  // following conditions:
  //
  // The above copyright notice and this permission notice shall be included
  // in all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
  // NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
  // DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  // USE OR OTHER DEALINGS IN THE SOFTWARE.
  // a transform stream is a readable/writable stream where you do
  // something with the data.  Sometimes it's called a "filter",
  // but that's not a great name for it, since that implies a thing where
  // some bits pass through, and others are simply ignored.  (That would
  // be a valid example of a transform, of course.)
  //
  // While the output is causally related to the input, it's not a
  // necessarily symmetric or synchronous transformation.  For example,
  // a zlib stream might take multiple plain-text writes(), and then
  // emit a single compressed chunk some time in the future.
  //
  // Here's how this works:
  //
  // The Transform stream has all the aspects of the readable and writable
  // stream classes.  When you write(chunk), that calls _write(chunk,cb)
  // internally, and returns false if there's a lot of pending writes
  // buffered up.  When you call read(), that calls _read(n) until
  // there's enough pending readable data buffered up.
  //
  // In a transform stream, the written data is placed in a buffer.  When
  // _read(n) is called, it transforms the queued up data, calling the
  // buffered _write cb's as it consumes chunks.  If consuming a single
  // written chunk would result in multiple output chunks, then the first
  // outputted bit calls the readcb, and subsequent chunks just go into
  // the read buffer, and will cause it to emit 'readable' if necessary.
  //
  // This way, back-pressure is actually determined by the reading side,
  // since _read has to be called to start processing a new chunk.  However,
  // a pathological inflate type of transform can cause excessive buffering
  // here.  For example, imagine a stream where every byte of input is
  // interpreted as an integer from 0-255, and then results in that many
  // bytes of output.  Writing the 4 bytes {ff,ff,ff,ff} would result in
  // 1kb of data being output.  In this case, you could write a very small
  // amount of input, and end up with a very large amount of output.  In
  // such a pathological inflating mechanism, there'd be no way to tell
  // the system to stop doing the transform.  A single 4MB write could
  // cause the system to run out of memory.
  //
  // However, even in such a pathological case, only a single written chunk
  // would be consumed, and then the rest would wait (un-transformed) until
  // the results of the previous transformed chunk were consumed.
  'use strict';
  
  module.exports = Transform;
  
  var _require$codes = require('../errors').codes,
      ERR_METHOD_NOT_IMPLEMENTED = _require$codes.ERR_METHOD_NOT_IMPLEMENTED,
      ERR_MULTIPLE_CALLBACK = _require$codes.ERR_MULTIPLE_CALLBACK,
      ERR_TRANSFORM_ALREADY_TRANSFORMING = _require$codes.ERR_TRANSFORM_ALREADY_TRANSFORMING,
      ERR_TRANSFORM_WITH_LENGTH_0 = _require$codes.ERR_TRANSFORM_WITH_LENGTH_0;
  
  var Duplex = require('./_stream_duplex');
  
  require('inherits')(Transform, Duplex);
  
  function afterTransform(er, data) {
    var ts = this._transformState;
    ts.transforming = false;
    var cb = ts.writecb;
  
    if (cb === null) {
      return this.emit('error', new ERR_MULTIPLE_CALLBACK());
    }
  
    ts.writechunk = null;
    ts.writecb = null;
    if (data != null) // single equals check for both `null` and `undefined`
      this.push(data);
    cb(er);
    var rs = this._readableState;
    rs.reading = false;
  
    if (rs.needReadable || rs.length < rs.highWaterMark) {
      this._read(rs.highWaterMark);
    }
  }
  
  function Transform(options) {
    if (!(this instanceof Transform)) return new Transform(options);
    Duplex.call(this, options);
    this._transformState = {
      afterTransform: afterTransform.bind(this),
      needTransform: false,
      transforming: false,
      writecb: null,
      writechunk: null,
      writeencoding: null
    }; // start out asking for a readable event once data is transformed.
  
    this._readableState.needReadable = true; // we have implemented the _read method, and done the other things
    // that Readable wants before the first _read call, so unset the
    // sync guard flag.
  
    this._readableState.sync = false;
  
    if (options) {
      if (typeof options.transform === 'function') this._transform = options.transform;
      if (typeof options.flush === 'function') this._flush = options.flush;
    } // When the writable side finishes, then flush out anything remaining.
  
  
    this.on('prefinish', prefinish);
  }
  
  function prefinish() {
    var _this = this;
  
    if (typeof this._flush === 'function' && !this._readableState.destroyed) {
      this._flush(function (er, data) {
        done(_this, er, data);
      });
    } else {
      done(this, null, null);
    }
  }
  
  Transform.prototype.push = function (chunk, encoding) {
    this._transformState.needTransform = false;
    return Duplex.prototype.push.call(this, chunk, encoding);
  }; // This is the part where you do stuff!
  // override this function in implementation classes.
  // 'chunk' is an input chunk.
  //
  // Call `push(newChunk)` to pass along transformed output
  // to the readable side.  You may call 'push' zero or more times.
  //
  // Call `cb(err)` when you are done with this chunk.  If you pass
  // an error, then that'll put the hurt on the whole operation.  If you
  // never call cb(), then you'll never get another chunk.
  
  
  Transform.prototype._transform = function (chunk, encoding, cb) {
    cb(new ERR_METHOD_NOT_IMPLEMENTED('_transform()'));
  };
  
  Transform.prototype._write = function (chunk, encoding, cb) {
    var ts = this._transformState;
    ts.writecb = cb;
    ts.writechunk = chunk;
    ts.writeencoding = encoding;
  
    if (!ts.transforming) {
      var rs = this._readableState;
      if (ts.needTransform || rs.needReadable || rs.length < rs.highWaterMark) this._read(rs.highWaterMark);
    }
  }; // Doesn't matter what the args are here.
  // _transform does all the work.
  // That we got here means that the readable side wants more data.
  
  
  Transform.prototype._read = function (n) {
    var ts = this._transformState;
  
    if (ts.writechunk !== null && !ts.transforming) {
      ts.transforming = true;
  
      this._transform(ts.writechunk, ts.writeencoding, ts.afterTransform);
    } else {
      // mark that we need a transform, so that any data that comes in
      // will get processed, now that we've asked for it.
      ts.needTransform = true;
    }
  };
  
  Transform.prototype._destroy = function (err, cb) {
    Duplex.prototype._destroy.call(this, err, function (err2) {
      cb(err2);
    });
  };
  
  function done(stream, er, data) {
    if (er) return stream.emit('error', er);
    if (data != null) // single equals check for both `null` and `undefined`
      stream.push(data); // TODO(BridgeAR): Write a test for these two error cases
    // if there's nothing in the write buffer, then that means
    // that nothing more will ever be provided
  
    if (stream._writableState.length) throw new ERR_TRANSFORM_WITH_LENGTH_0();
    if (stream._transformState.transforming) throw new ERR_TRANSFORM_ALREADY_TRANSFORMING();
    return stream.push(null);
  }
  },{"../errors":45,"./_stream_duplex":46,"inherits":29}],50:[function(require,module,exports){
  (function (process,global){
  // Copyright Joyent, Inc. and other Node contributors.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a
  // copy of this software and associated documentation files (the
  // "Software"), to deal in the Software without restriction, including
  // without limitation the rights to use, copy, modify, merge, publish,
  // distribute, sublicense, and/or sell copies of the Software, and to permit
  // persons to whom the Software is furnished to do so, subject to the
  // following conditions:
  //
  // The above copyright notice and this permission notice shall be included
  // in all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
  // NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
  // DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  // USE OR OTHER DEALINGS IN THE SOFTWARE.
  // A bit simpler than readable streams.
  // Implement an async ._write(chunk, encoding, cb), and it'll handle all
  // the drain event emission and buffering.
  'use strict';
  
  module.exports = Writable;
  /* <replacement> */
  
  function WriteReq(chunk, encoding, cb) {
    this.chunk = chunk;
    this.encoding = encoding;
    this.callback = cb;
    this.next = null;
  } // It seems a linked list but it is not
  // there will be only 2 of these for each stream
  
  
  function CorkedRequest(state) {
    var _this = this;
  
    this.next = null;
    this.entry = null;
  
    this.finish = function () {
      onCorkedFinish(_this, state);
    };
  }
  /* </replacement> */
  
  /*<replacement>*/
  
  
  var Duplex;
  /*</replacement>*/
  
  Writable.WritableState = WritableState;
  /*<replacement>*/
  
  var internalUtil = {
    deprecate: require('util-deprecate')
  };
  /*</replacement>*/
  
  /*<replacement>*/
  
  var Stream = require('./internal/streams/stream');
  /*</replacement>*/
  
  
  var Buffer = require('buffer').Buffer;
  
  var OurUint8Array = global.Uint8Array || function () {};
  
  function _uint8ArrayToBuffer(chunk) {
    return Buffer.from(chunk);
  }
  
  function _isUint8Array(obj) {
    return Buffer.isBuffer(obj) || obj instanceof OurUint8Array;
  }
  
  var destroyImpl = require('./internal/streams/destroy');
  
  var _require = require('./internal/streams/state'),
      getHighWaterMark = _require.getHighWaterMark;
  
  var _require$codes = require('../errors').codes,
      ERR_INVALID_ARG_TYPE = _require$codes.ERR_INVALID_ARG_TYPE,
      ERR_METHOD_NOT_IMPLEMENTED = _require$codes.ERR_METHOD_NOT_IMPLEMENTED,
      ERR_MULTIPLE_CALLBACK = _require$codes.ERR_MULTIPLE_CALLBACK,
      ERR_STREAM_CANNOT_PIPE = _require$codes.ERR_STREAM_CANNOT_PIPE,
      ERR_STREAM_DESTROYED = _require$codes.ERR_STREAM_DESTROYED,
      ERR_STREAM_NULL_VALUES = _require$codes.ERR_STREAM_NULL_VALUES,
      ERR_STREAM_WRITE_AFTER_END = _require$codes.ERR_STREAM_WRITE_AFTER_END,
      ERR_UNKNOWN_ENCODING = _require$codes.ERR_UNKNOWN_ENCODING;
  
  var errorOrDestroy = destroyImpl.errorOrDestroy;
  
  require('inherits')(Writable, Stream);
  
  function nop() {}
  
  function WritableState(options, stream, isDuplex) {
    Duplex = Duplex || require('./_stream_duplex');
    options = options || {}; // Duplex streams are both readable and writable, but share
    // the same options object.
    // However, some cases require setting options to different
    // values for the readable and the writable sides of the duplex stream,
    // e.g. options.readableObjectMode vs. options.writableObjectMode, etc.
  
    if (typeof isDuplex !== 'boolean') isDuplex = stream instanceof Duplex; // object stream flag to indicate whether or not this stream
    // contains buffers or objects.
  
    this.objectMode = !!options.objectMode;
    if (isDuplex) this.objectMode = this.objectMode || !!options.writableObjectMode; // the point at which write() starts returning false
    // Note: 0 is a valid value, means that we always return false if
    // the entire buffer is not flushed immediately on write()
  
    this.highWaterMark = getHighWaterMark(this, options, 'writableHighWaterMark', isDuplex); // if _final has been called
  
    this.finalCalled = false; // drain event flag.
  
    this.needDrain = false; // at the start of calling end()
  
    this.ending = false; // when end() has been called, and returned
  
    this.ended = false; // when 'finish' is emitted
  
    this.finished = false; // has it been destroyed
  
    this.destroyed = false; // should we decode strings into buffers before passing to _write?
    // this is here so that some node-core streams can optimize string
    // handling at a lower level.
  
    var noDecode = options.decodeStrings === false;
    this.decodeStrings = !noDecode; // Crypto is kind of old and crusty.  Historically, its default string
    // encoding is 'binary' so we have to make this configurable.
    // Everything else in the universe uses 'utf8', though.
  
    this.defaultEncoding = options.defaultEncoding || 'utf8'; // not an actual buffer we keep track of, but a measurement
    // of how much we're waiting to get pushed to some underlying
    // socket or file.
  
    this.length = 0; // a flag to see when we're in the middle of a write.
  
    this.writing = false; // when true all writes will be buffered until .uncork() call
  
    this.corked = 0; // a flag to be able to tell if the onwrite cb is called immediately,
    // or on a later tick.  We set this to true at first, because any
    // actions that shouldn't happen until "later" should generally also
    // not happen before the first write call.
  
    this.sync = true; // a flag to know if we're processing previously buffered items, which
    // may call the _write() callback in the same tick, so that we don't
    // end up in an overlapped onwrite situation.
  
    this.bufferProcessing = false; // the callback that's passed to _write(chunk,cb)
  
    this.onwrite = function (er) {
      onwrite(stream, er);
    }; // the callback that the user supplies to write(chunk,encoding,cb)
  
  
    this.writecb = null; // the amount that is being written when _write is called.
  
    this.writelen = 0;
    this.bufferedRequest = null;
    this.lastBufferedRequest = null; // number of pending user-supplied write callbacks
    // this must be 0 before 'finish' can be emitted
  
    this.pendingcb = 0; // emit prefinish if the only thing we're waiting for is _write cbs
    // This is relevant for synchronous Transform streams
  
    this.prefinished = false; // True if the error was already emitted and should not be thrown again
  
    this.errorEmitted = false; // Should close be emitted on destroy. Defaults to true.
  
    this.emitClose = options.emitClose !== false; // Should .destroy() be called after 'finish' (and potentially 'end')
  
    this.autoDestroy = !!options.autoDestroy; // count buffered requests
  
    this.bufferedRequestCount = 0; // allocate the first CorkedRequest, there is always
    // one allocated and free to use, and we maintain at most two
  
    this.corkedRequestsFree = new CorkedRequest(this);
  }
  
  WritableState.prototype.getBuffer = function getBuffer() {
    var current = this.bufferedRequest;
    var out = [];
  
    while (current) {
      out.push(current);
      current = current.next;
    }
  
    return out;
  };
  
  (function () {
    try {
      Object.defineProperty(WritableState.prototype, 'buffer', {
        get: internalUtil.deprecate(function writableStateBufferGetter() {
          return this.getBuffer();
        }, '_writableState.buffer is deprecated. Use _writableState.getBuffer ' + 'instead.', 'DEP0003')
      });
    } catch (_) {}
  })(); // Test _writableState for inheritance to account for Duplex streams,
  // whose prototype chain only points to Readable.
  
  
  var realHasInstance;
  
  if (typeof Symbol === 'function' && Symbol.hasInstance && typeof Function.prototype[Symbol.hasInstance] === 'function') {
    realHasInstance = Function.prototype[Symbol.hasInstance];
    Object.defineProperty(Writable, Symbol.hasInstance, {
      value: function value(object) {
        if (realHasInstance.call(this, object)) return true;
        if (this !== Writable) return false;
        return object && object._writableState instanceof WritableState;
      }
    });
  } else {
    realHasInstance = function realHasInstance(object) {
      return object instanceof this;
    };
  }
  
  function Writable(options) {
    Duplex = Duplex || require('./_stream_duplex'); // Writable ctor is applied to Duplexes, too.
    // `realHasInstance` is necessary because using plain `instanceof`
    // would return false, as no `_writableState` property is attached.
    // Trying to use the custom `instanceof` for Writable here will also break the
    // Node.js LazyTransform implementation, which has a non-trivial getter for
    // `_writableState` that would lead to infinite recursion.
    // Checking for a Stream.Duplex instance is faster here instead of inside
    // the WritableState constructor, at least with V8 6.5
  
    var isDuplex = this instanceof Duplex;
    if (!isDuplex && !realHasInstance.call(Writable, this)) return new Writable(options);
    this._writableState = new WritableState(options, this, isDuplex); // legacy.
  
    this.writable = true;
  
    if (options) {
      if (typeof options.write === 'function') this._write = options.write;
      if (typeof options.writev === 'function') this._writev = options.writev;
      if (typeof options.destroy === 'function') this._destroy = options.destroy;
      if (typeof options.final === 'function') this._final = options.final;
    }
  
    Stream.call(this);
  } // Otherwise people can pipe Writable streams, which is just wrong.
  
  
  Writable.prototype.pipe = function () {
    errorOrDestroy(this, new ERR_STREAM_CANNOT_PIPE());
  };
  
  function writeAfterEnd(stream, cb) {
    var er = new ERR_STREAM_WRITE_AFTER_END(); // TODO: defer error events consistently everywhere, not just the cb
  
    errorOrDestroy(stream, er);
    process.nextTick(cb, er);
  } // Checks that a user-supplied chunk is valid, especially for the particular
  // mode the stream is in. Currently this means that `null` is never accepted
  // and undefined/non-string values are only allowed in object mode.
  
  
  function validChunk(stream, state, chunk, cb) {
    var er;
  
    if (chunk === null) {
      er = new ERR_STREAM_NULL_VALUES();
    } else if (typeof chunk !== 'string' && !state.objectMode) {
      er = new ERR_INVALID_ARG_TYPE('chunk', ['string', 'Buffer'], chunk);
    }
  
    if (er) {
      errorOrDestroy(stream, er);
      process.nextTick(cb, er);
      return false;
    }
  
    return true;
  }
  
  Writable.prototype.write = function (chunk, encoding, cb) {
    var state = this._writableState;
    var ret = false;
  
    var isBuf = !state.objectMode && _isUint8Array(chunk);
  
    if (isBuf && !Buffer.isBuffer(chunk)) {
      chunk = _uint8ArrayToBuffer(chunk);
    }
  
    if (typeof encoding === 'function') {
      cb = encoding;
      encoding = null;
    }
  
    if (isBuf) encoding = 'buffer';else if (!encoding) encoding = state.defaultEncoding;
    if (typeof cb !== 'function') cb = nop;
    if (state.ending) writeAfterEnd(this, cb);else if (isBuf || validChunk(this, state, chunk, cb)) {
      state.pendingcb++;
      ret = writeOrBuffer(this, state, isBuf, chunk, encoding, cb);
    }
    return ret;
  };
  
  Writable.prototype.cork = function () {
    this._writableState.corked++;
  };
  
  Writable.prototype.uncork = function () {
    var state = this._writableState;
  
    if (state.corked) {
      state.corked--;
      if (!state.writing && !state.corked && !state.bufferProcessing && state.bufferedRequest) clearBuffer(this, state);
    }
  };
  
  Writable.prototype.setDefaultEncoding = function setDefaultEncoding(encoding) {
    // node::ParseEncoding() requires lower case.
    if (typeof encoding === 'string') encoding = encoding.toLowerCase();
    if (!(['hex', 'utf8', 'utf-8', 'ascii', 'binary', 'base64', 'ucs2', 'ucs-2', 'utf16le', 'utf-16le', 'raw'].indexOf((encoding + '').toLowerCase()) > -1)) throw new ERR_UNKNOWN_ENCODING(encoding);
    this._writableState.defaultEncoding = encoding;
    return this;
  };
  
  Object.defineProperty(Writable.prototype, 'writableBuffer', {
    // making it explicit this property is not enumerable
    // because otherwise some prototype manipulation in
    // userland will fail
    enumerable: false,
    get: function get() {
      return this._writableState && this._writableState.getBuffer();
    }
  });
  
  function decodeChunk(state, chunk, encoding) {
    if (!state.objectMode && state.decodeStrings !== false && typeof chunk === 'string') {
      chunk = Buffer.from(chunk, encoding);
    }
  
    return chunk;
  }
  
  Object.defineProperty(Writable.prototype, 'writableHighWaterMark', {
    // making it explicit this property is not enumerable
    // because otherwise some prototype manipulation in
    // userland will fail
    enumerable: false,
    get: function get() {
      return this._writableState.highWaterMark;
    }
  }); // if we're already writing something, then just put this
  // in the queue, and wait our turn.  Otherwise, call _write
  // If we return false, then we need a drain event, so set that flag.
  
  function writeOrBuffer(stream, state, isBuf, chunk, encoding, cb) {
    if (!isBuf) {
      var newChunk = decodeChunk(state, chunk, encoding);
  
      if (chunk !== newChunk) {
        isBuf = true;
        encoding = 'buffer';
        chunk = newChunk;
      }
    }
  
    var len = state.objectMode ? 1 : chunk.length;
    state.length += len;
    var ret = state.length < state.highWaterMark; // we must ensure that previous needDrain will not be reset to false.
  
    if (!ret) state.needDrain = true;
  
    if (state.writing || state.corked) {
      var last = state.lastBufferedRequest;
      state.lastBufferedRequest = {
        chunk: chunk,
        encoding: encoding,
        isBuf: isBuf,
        callback: cb,
        next: null
      };
  
      if (last) {
        last.next = state.lastBufferedRequest;
      } else {
        state.bufferedRequest = state.lastBufferedRequest;
      }
  
      state.bufferedRequestCount += 1;
    } else {
      doWrite(stream, state, false, len, chunk, encoding, cb);
    }
  
    return ret;
  }
  
  function doWrite(stream, state, writev, len, chunk, encoding, cb) {
    state.writelen = len;
    state.writecb = cb;
    state.writing = true;
    state.sync = true;
    if (state.destroyed) state.onwrite(new ERR_STREAM_DESTROYED('write'));else if (writev) stream._writev(chunk, state.onwrite);else stream._write(chunk, encoding, state.onwrite);
    state.sync = false;
  }
  
  function onwriteError(stream, state, sync, er, cb) {
    --state.pendingcb;
  
    if (sync) {
      // defer the callback if we are being called synchronously
      // to avoid piling up things on the stack
      process.nextTick(cb, er); // this can emit finish, and it will always happen
      // after error
  
      process.nextTick(finishMaybe, stream, state);
      stream._writableState.errorEmitted = true;
      errorOrDestroy(stream, er);
    } else {
      // the caller expect this to happen before if
      // it is async
      cb(er);
      stream._writableState.errorEmitted = true;
      errorOrDestroy(stream, er); // this can emit finish, but finish must
      // always follow error
  
      finishMaybe(stream, state);
    }
  }
  
  function onwriteStateUpdate(state) {
    state.writing = false;
    state.writecb = null;
    state.length -= state.writelen;
    state.writelen = 0;
  }
  
  function onwrite(stream, er) {
    var state = stream._writableState;
    var sync = state.sync;
    var cb = state.writecb;
    if (typeof cb !== 'function') throw new ERR_MULTIPLE_CALLBACK();
    onwriteStateUpdate(state);
    if (er) onwriteError(stream, state, sync, er, cb);else {
      // Check if we're actually ready to finish, but don't emit yet
      var finished = needFinish(state) || stream.destroyed;
  
      if (!finished && !state.corked && !state.bufferProcessing && state.bufferedRequest) {
        clearBuffer(stream, state);
      }
  
      if (sync) {
        process.nextTick(afterWrite, stream, state, finished, cb);
      } else {
        afterWrite(stream, state, finished, cb);
      }
    }
  }
  
  function afterWrite(stream, state, finished, cb) {
    if (!finished) onwriteDrain(stream, state);
    state.pendingcb--;
    cb();
    finishMaybe(stream, state);
  } // Must force callback to be called on nextTick, so that we don't
  // emit 'drain' before the write() consumer gets the 'false' return
  // value, and has a chance to attach a 'drain' listener.
  
  
  function onwriteDrain(stream, state) {
    if (state.length === 0 && state.needDrain) {
      state.needDrain = false;
      stream.emit('drain');
    }
  } // if there's something in the buffer waiting, then process it
  
  
  function clearBuffer(stream, state) {
    state.bufferProcessing = true;
    var entry = state.bufferedRequest;
  
    if (stream._writev && entry && entry.next) {
      // Fast case, write everything using _writev()
      var l = state.bufferedRequestCount;
      var buffer = new Array(l);
      var holder = state.corkedRequestsFree;
      holder.entry = entry;
      var count = 0;
      var allBuffers = true;
  
      while (entry) {
        buffer[count] = entry;
        if (!entry.isBuf) allBuffers = false;
        entry = entry.next;
        count += 1;
      }
  
      buffer.allBuffers = allBuffers;
      doWrite(stream, state, true, state.length, buffer, '', holder.finish); // doWrite is almost always async, defer these to save a bit of time
      // as the hot path ends with doWrite
  
      state.pendingcb++;
      state.lastBufferedRequest = null;
  
      if (holder.next) {
        state.corkedRequestsFree = holder.next;
        holder.next = null;
      } else {
        state.corkedRequestsFree = new CorkedRequest(state);
      }
  
      state.bufferedRequestCount = 0;
    } else {
      // Slow case, write chunks one-by-one
      while (entry) {
        var chunk = entry.chunk;
        var encoding = entry.encoding;
        var cb = entry.callback;
        var len = state.objectMode ? 1 : chunk.length;
        doWrite(stream, state, false, len, chunk, encoding, cb);
        entry = entry.next;
        state.bufferedRequestCount--; // if we didn't call the onwrite immediately, then
        // it means that we need to wait until it does.
        // also, that means that the chunk and cb are currently
        // being processed, so move the buffer counter past them.
  
        if (state.writing) {
          break;
        }
      }
  
      if (entry === null) state.lastBufferedRequest = null;
    }
  
    state.bufferedRequest = entry;
    state.bufferProcessing = false;
  }
  
  Writable.prototype._write = function (chunk, encoding, cb) {
    cb(new ERR_METHOD_NOT_IMPLEMENTED('_write()'));
  };
  
  Writable.prototype._writev = null;
  
  Writable.prototype.end = function (chunk, encoding, cb) {
    var state = this._writableState;
  
    if (typeof chunk === 'function') {
      cb = chunk;
      chunk = null;
      encoding = null;
    } else if (typeof encoding === 'function') {
      cb = encoding;
      encoding = null;
    }
  
    if (chunk !== null && chunk !== undefined) this.write(chunk, encoding); // .end() fully uncorks
  
    if (state.corked) {
      state.corked = 1;
      this.uncork();
    } // ignore unnecessary end() calls.
  
  
    if (!state.ending) endWritable(this, state, cb);
    return this;
  };
  
  Object.defineProperty(Writable.prototype, 'writableLength', {
    // making it explicit this property is not enumerable
    // because otherwise some prototype manipulation in
    // userland will fail
    enumerable: false,
    get: function get() {
      return this._writableState.length;
    }
  });
  
  function needFinish(state) {
    return state.ending && state.length === 0 && state.bufferedRequest === null && !state.finished && !state.writing;
  }
  
  function callFinal(stream, state) {
    stream._final(function (err) {
      state.pendingcb--;
  
      if (err) {
        errorOrDestroy(stream, err);
      }
  
      state.prefinished = true;
      stream.emit('prefinish');
      finishMaybe(stream, state);
    });
  }
  
  function prefinish(stream, state) {
    if (!state.prefinished && !state.finalCalled) {
      if (typeof stream._final === 'function' && !state.destroyed) {
        state.pendingcb++;
        state.finalCalled = true;
        process.nextTick(callFinal, stream, state);
      } else {
        state.prefinished = true;
        stream.emit('prefinish');
      }
    }
  }
  
  function finishMaybe(stream, state) {
    var need = needFinish(state);
  
    if (need) {
      prefinish(stream, state);
  
      if (state.pendingcb === 0) {
        state.finished = true;
        stream.emit('finish');
  
        if (state.autoDestroy) {
          // In case of duplex streams we need a way to detect
          // if the readable side is ready for autoDestroy as well
          var rState = stream._readableState;
  
          if (!rState || rState.autoDestroy && rState.endEmitted) {
            stream.destroy();
          }
        }
      }
    }
  
    return need;
  }
  
  function endWritable(stream, state, cb) {
    state.ending = true;
    finishMaybe(stream, state);
  
    if (cb) {
      if (state.finished) process.nextTick(cb);else stream.once('finish', cb);
    }
  
    state.ended = true;
    stream.writable = false;
  }
  
  function onCorkedFinish(corkReq, state, err) {
    var entry = corkReq.entry;
    corkReq.entry = null;
  
    while (entry) {
      var cb = entry.callback;
      state.pendingcb--;
      cb(err);
      entry = entry.next;
    } // reuse the free corkReq.
  
  
    state.corkedRequestsFree.next = corkReq;
  }
  
  Object.defineProperty(Writable.prototype, 'destroyed', {
    // making it explicit this property is not enumerable
    // because otherwise some prototype manipulation in
    // userland will fail
    enumerable: false,
    get: function get() {
      if (this._writableState === undefined) {
        return false;
      }
  
      return this._writableState.destroyed;
    },
    set: function set(value) {
      // we ignore the value if the stream
      // has not been initialized yet
      if (!this._writableState) {
        return;
      } // backward compatibility, the user is explicitly
      // managing destroyed
  
  
      this._writableState.destroyed = value;
    }
  });
  Writable.prototype.destroy = destroyImpl.destroy;
  Writable.prototype._undestroy = destroyImpl.undestroy;
  
  Writable.prototype._destroy = function (err, cb) {
    cb(err);
  };
  }).call(this,require('_process'),typeof global !== "undefined" ? global : typeof self !== "undefined" ? self : typeof window !== "undefined" ? window : {})
  },{"../errors":45,"./_stream_duplex":46,"./internal/streams/destroy":53,"./internal/streams/state":57,"./internal/streams/stream":58,"_process":44,"buffer":12,"inherits":29,"util-deprecate":65}],51:[function(require,module,exports){
  (function (process){
  'use strict';
  
  var _Object$setPrototypeO;
  
  function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }
  
  var finished = require('./end-of-stream');
  
  var kLastResolve = Symbol('lastResolve');
  var kLastReject = Symbol('lastReject');
  var kError = Symbol('error');
  var kEnded = Symbol('ended');
  var kLastPromise = Symbol('lastPromise');
  var kHandlePromise = Symbol('handlePromise');
  var kStream = Symbol('stream');
  
  function createIterResult(value, done) {
    return {
      value: value,
      done: done
    };
  }
  
  function readAndResolve(iter) {
    var resolve = iter[kLastResolve];
  
    if (resolve !== null) {
      var data = iter[kStream].read(); // we defer if data is null
      // we can be expecting either 'end' or
      // 'error'
  
      if (data !== null) {
        iter[kLastPromise] = null;
        iter[kLastResolve] = null;
        iter[kLastReject] = null;
        resolve(createIterResult(data, false));
      }
    }
  }
  
  function onReadable(iter) {
    // we wait for the next tick, because it might
    // emit an error with process.nextTick
    process.nextTick(readAndResolve, iter);
  }
  
  function wrapForNext(lastPromise, iter) {
    return function (resolve, reject) {
      lastPromise.then(function () {
        if (iter[kEnded]) {
          resolve(createIterResult(undefined, true));
          return;
        }
  
        iter[kHandlePromise](resolve, reject);
      }, reject);
    };
  }
  
  var AsyncIteratorPrototype = Object.getPrototypeOf(function () {});
  var ReadableStreamAsyncIteratorPrototype = Object.setPrototypeOf((_Object$setPrototypeO = {
    get stream() {
      return this[kStream];
    },
  
    next: function next() {
      var _this = this;
  
      // if we have detected an error in the meanwhile
      // reject straight away
      var error = this[kError];
  
      if (error !== null) {
        return Promise.reject(error);
      }
  
      if (this[kEnded]) {
        return Promise.resolve(createIterResult(undefined, true));
      }
  
      if (this[kStream].destroyed) {
        // We need to defer via nextTick because if .destroy(err) is
        // called, the error will be emitted via nextTick, and
        // we cannot guarantee that there is no error lingering around
        // waiting to be emitted.
        return new Promise(function (resolve, reject) {
          process.nextTick(function () {
            if (_this[kError]) {
              reject(_this[kError]);
            } else {
              resolve(createIterResult(undefined, true));
            }
          });
        });
      } // if we have multiple next() calls
      // we will wait for the previous Promise to finish
      // this logic is optimized to support for await loops,
      // where next() is only called once at a time
  
  
      var lastPromise = this[kLastPromise];
      var promise;
  
      if (lastPromise) {
        promise = new Promise(wrapForNext(lastPromise, this));
      } else {
        // fast path needed to support multiple this.push()
        // without triggering the next() queue
        var data = this[kStream].read();
  
        if (data !== null) {
          return Promise.resolve(createIterResult(data, false));
        }
  
        promise = new Promise(this[kHandlePromise]);
      }
  
      this[kLastPromise] = promise;
      return promise;
    }
  }, _defineProperty(_Object$setPrototypeO, Symbol.asyncIterator, function () {
    return this;
  }), _defineProperty(_Object$setPrototypeO, "return", function _return() {
    var _this2 = this;
  
    // destroy(err, cb) is a private API
    // we can guarantee we have that here, because we control the
    // Readable class this is attached to
    return new Promise(function (resolve, reject) {
      _this2[kStream].destroy(null, function (err) {
        if (err) {
          reject(err);
          return;
        }
  
        resolve(createIterResult(undefined, true));
      });
    });
  }), _Object$setPrototypeO), AsyncIteratorPrototype);
  
  var createReadableStreamAsyncIterator = function createReadableStreamAsyncIterator(stream) {
    var _Object$create;
  
    var iterator = Object.create(ReadableStreamAsyncIteratorPrototype, (_Object$create = {}, _defineProperty(_Object$create, kStream, {
      value: stream,
      writable: true
    }), _defineProperty(_Object$create, kLastResolve, {
      value: null,
      writable: true
    }), _defineProperty(_Object$create, kLastReject, {
      value: null,
      writable: true
    }), _defineProperty(_Object$create, kError, {
      value: null,
      writable: true
    }), _defineProperty(_Object$create, kEnded, {
      value: stream._readableState.endEmitted,
      writable: true
    }), _defineProperty(_Object$create, kHandlePromise, {
      value: function value(resolve, reject) {
        var data = iterator[kStream].read();
  
        if (data) {
          iterator[kLastPromise] = null;
          iterator[kLastResolve] = null;
          iterator[kLastReject] = null;
          resolve(createIterResult(data, false));
        } else {
          iterator[kLastResolve] = resolve;
          iterator[kLastReject] = reject;
        }
      },
      writable: true
    }), _Object$create));
    iterator[kLastPromise] = null;
    finished(stream, function (err) {
      if (err && err.code !== 'ERR_STREAM_PREMATURE_CLOSE') {
        var reject = iterator[kLastReject]; // reject if we are waiting for data in the Promise
        // returned by next() and store the error
  
        if (reject !== null) {
          iterator[kLastPromise] = null;
          iterator[kLastResolve] = null;
          iterator[kLastReject] = null;
          reject(err);
        }
  
        iterator[kError] = err;
        return;
      }
  
      var resolve = iterator[kLastResolve];
  
      if (resolve !== null) {
        iterator[kLastPromise] = null;
        iterator[kLastResolve] = null;
        iterator[kLastReject] = null;
        resolve(createIterResult(undefined, true));
      }
  
      iterator[kEnded] = true;
    });
    stream.on('readable', onReadable.bind(null, iterator));
    return iterator;
  };
  
  module.exports = createReadableStreamAsyncIterator;
  }).call(this,require('_process'))
  },{"./end-of-stream":54,"_process":44}],52:[function(require,module,exports){
  'use strict';
  
  function ownKeys(object, enumerableOnly) { var keys = Object.keys(object); if (Object.getOwnPropertySymbols) { var symbols = Object.getOwnPropertySymbols(object); if (enumerableOnly) symbols = symbols.filter(function (sym) { return Object.getOwnPropertyDescriptor(object, sym).enumerable; }); keys.push.apply(keys, symbols); } return keys; }
  
  function _objectSpread(target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i] != null ? arguments[i] : {}; if (i % 2) { ownKeys(Object(source), true).forEach(function (key) { _defineProperty(target, key, source[key]); }); } else if (Object.getOwnPropertyDescriptors) { Object.defineProperties(target, Object.getOwnPropertyDescriptors(source)); } else { ownKeys(Object(source)).forEach(function (key) { Object.defineProperty(target, key, Object.getOwnPropertyDescriptor(source, key)); }); } } return target; }
  
  function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }
  
  function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
  
  function _defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } }
  
  function _createClass(Constructor, protoProps, staticProps) { if (protoProps) _defineProperties(Constructor.prototype, protoProps); if (staticProps) _defineProperties(Constructor, staticProps); return Constructor; }
  
  var _require = require('buffer'),
      Buffer = _require.Buffer;
  
  var _require2 = require('util'),
      inspect = _require2.inspect;
  
  var custom = inspect && inspect.custom || 'inspect';
  
  function copyBuffer(src, target, offset) {
    Buffer.prototype.copy.call(src, target, offset);
  }
  
  module.exports =
  /*#__PURE__*/
  function () {
    function BufferList() {
      _classCallCheck(this, BufferList);
  
      this.head = null;
      this.tail = null;
      this.length = 0;
    }
  
    _createClass(BufferList, [{
      key: "push",
      value: function push(v) {
        var entry = {
          data: v,
          next: null
        };
        if (this.length > 0) this.tail.next = entry;else this.head = entry;
        this.tail = entry;
        ++this.length;
      }
    }, {
      key: "unshift",
      value: function unshift(v) {
        var entry = {
          data: v,
          next: this.head
        };
        if (this.length === 0) this.tail = entry;
        this.head = entry;
        ++this.length;
      }
    }, {
      key: "shift",
      value: function shift() {
        if (this.length === 0) return;
        var ret = this.head.data;
        if (this.length === 1) this.head = this.tail = null;else this.head = this.head.next;
        --this.length;
        return ret;
      }
    }, {
      key: "clear",
      value: function clear() {
        this.head = this.tail = null;
        this.length = 0;
      }
    }, {
      key: "join",
      value: function join(s) {
        if (this.length === 0) return '';
        var p = this.head;
        var ret = '' + p.data;
  
        while (p = p.next) {
          ret += s + p.data;
        }
  
        return ret;
      }
    }, {
      key: "concat",
      value: function concat(n) {
        if (this.length === 0) return Buffer.alloc(0);
        var ret = Buffer.allocUnsafe(n >>> 0);
        var p = this.head;
        var i = 0;
  
        while (p) {
          copyBuffer(p.data, ret, i);
          i += p.data.length;
          p = p.next;
        }
  
        return ret;
      } // Consumes a specified amount of bytes or characters from the buffered data.
  
    }, {
      key: "consume",
      value: function consume(n, hasStrings) {
        var ret;
  
        if (n < this.head.data.length) {
          // `slice` is the same for buffers and strings.
          ret = this.head.data.slice(0, n);
          this.head.data = this.head.data.slice(n);
        } else if (n === this.head.data.length) {
          // First chunk is a perfect match.
          ret = this.shift();
        } else {
          // Result spans more than one buffer.
          ret = hasStrings ? this._getString(n) : this._getBuffer(n);
        }
  
        return ret;
      }
    }, {
      key: "first",
      value: function first() {
        return this.head.data;
      } // Consumes a specified amount of characters from the buffered data.
  
    }, {
      key: "_getString",
      value: function _getString(n) {
        var p = this.head;
        var c = 1;
        var ret = p.data;
        n -= ret.length;
  
        while (p = p.next) {
          var str = p.data;
          var nb = n > str.length ? str.length : n;
          if (nb === str.length) ret += str;else ret += str.slice(0, n);
          n -= nb;
  
          if (n === 0) {
            if (nb === str.length) {
              ++c;
              if (p.next) this.head = p.next;else this.head = this.tail = null;
            } else {
              this.head = p;
              p.data = str.slice(nb);
            }
  
            break;
          }
  
          ++c;
        }
  
        this.length -= c;
        return ret;
      } // Consumes a specified amount of bytes from the buffered data.
  
    }, {
      key: "_getBuffer",
      value: function _getBuffer(n) {
        var ret = Buffer.allocUnsafe(n);
        var p = this.head;
        var c = 1;
        p.data.copy(ret);
        n -= p.data.length;
  
        while (p = p.next) {
          var buf = p.data;
          var nb = n > buf.length ? buf.length : n;
          buf.copy(ret, ret.length - n, 0, nb);
          n -= nb;
  
          if (n === 0) {
            if (nb === buf.length) {
              ++c;
              if (p.next) this.head = p.next;else this.head = this.tail = null;
            } else {
              this.head = p;
              p.data = buf.slice(nb);
            }
  
            break;
          }
  
          ++c;
        }
  
        this.length -= c;
        return ret;
      } // Make sure the linked list only shows the minimal necessary information.
  
    }, {
      key: custom,
      value: function value(_, options) {
        return inspect(this, _objectSpread({}, options, {
          // Only inspect one level.
          depth: 0,
          // It should not recurse.
          customInspect: false
        }));
      }
    }]);
  
    return BufferList;
  }();
  },{"buffer":12,"util":11}],53:[function(require,module,exports){
  (function (process){
  'use strict'; // undocumented cb() API, needed for core, not for public API
  
  function destroy(err, cb) {
    var _this = this;
  
    var readableDestroyed = this._readableState && this._readableState.destroyed;
    var writableDestroyed = this._writableState && this._writableState.destroyed;
  
    if (readableDestroyed || writableDestroyed) {
      if (cb) {
        cb(err);
      } else if (err) {
        if (!this._writableState) {
          process.nextTick(emitErrorNT, this, err);
        } else if (!this._writableState.errorEmitted) {
          this._writableState.errorEmitted = true;
          process.nextTick(emitErrorNT, this, err);
        }
      }
  
      return this;
    } // we set destroyed to true before firing error callbacks in order
    // to make it re-entrance safe in case destroy() is called within callbacks
  
  
    if (this._readableState) {
      this._readableState.destroyed = true;
    } // if this is a duplex stream mark the writable part as destroyed as well
  
  
    if (this._writableState) {
      this._writableState.destroyed = true;
    }
  
    this._destroy(err || null, function (err) {
      if (!cb && err) {
        if (!_this._writableState) {
          process.nextTick(emitErrorAndCloseNT, _this, err);
        } else if (!_this._writableState.errorEmitted) {
          _this._writableState.errorEmitted = true;
          process.nextTick(emitErrorAndCloseNT, _this, err);
        } else {
          process.nextTick(emitCloseNT, _this);
        }
      } else if (cb) {
        process.nextTick(emitCloseNT, _this);
        cb(err);
      } else {
        process.nextTick(emitCloseNT, _this);
      }
    });
  
    return this;
  }
  
  function emitErrorAndCloseNT(self, err) {
    emitErrorNT(self, err);
    emitCloseNT(self);
  }
  
  function emitCloseNT(self) {
    if (self._writableState && !self._writableState.emitClose) return;
    if (self._readableState && !self._readableState.emitClose) return;
    self.emit('close');
  }
  
  function undestroy() {
    if (this._readableState) {
      this._readableState.destroyed = false;
      this._readableState.reading = false;
      this._readableState.ended = false;
      this._readableState.endEmitted = false;
    }
  
    if (this._writableState) {
      this._writableState.destroyed = false;
      this._writableState.ended = false;
      this._writableState.ending = false;
      this._writableState.finalCalled = false;
      this._writableState.prefinished = false;
      this._writableState.finished = false;
      this._writableState.errorEmitted = false;
    }
  }
  
  function emitErrorNT(self, err) {
    self.emit('error', err);
  }
  
  function errorOrDestroy(stream, err) {
    // We have tests that rely on errors being emitted
    // in the same tick, so changing this is semver major.
    // For now when you opt-in to autoDestroy we allow
    // the error to be emitted nextTick. In a future
    // semver major update we should change the default to this.
    var rState = stream._readableState;
    var wState = stream._writableState;
    if (rState && rState.autoDestroy || wState && wState.autoDestroy) stream.destroy(err);else stream.emit('error', err);
  }
  
  module.exports = {
    destroy: destroy,
    undestroy: undestroy,
    errorOrDestroy: errorOrDestroy
  };
  }).call(this,require('_process'))
  },{"_process":44}],54:[function(require,module,exports){
  // Ported from https://github.com/mafintosh/end-of-stream with
  // permission from the author, Mathias Buus (@mafintosh).
  'use strict';
  
  var ERR_STREAM_PREMATURE_CLOSE = require('../../../errors').codes.ERR_STREAM_PREMATURE_CLOSE;
  
  function once(callback) {
    var called = false;
    return function () {
      if (called) return;
      called = true;
  
      for (var _len = arguments.length, args = new Array(_len), _key = 0; _key < _len; _key++) {
        args[_key] = arguments[_key];
      }
  
      callback.apply(this, args);
    };
  }
  
  function noop() {}
  
  function isRequest(stream) {
    return stream.setHeader && typeof stream.abort === 'function';
  }
  
  function eos(stream, opts, callback) {
    if (typeof opts === 'function') return eos(stream, null, opts);
    if (!opts) opts = {};
    callback = once(callback || noop);
    var readable = opts.readable || opts.readable !== false && stream.readable;
    var writable = opts.writable || opts.writable !== false && stream.writable;
  
    var onlegacyfinish = function onlegacyfinish() {
      if (!stream.writable) onfinish();
    };
  
    var writableEnded = stream._writableState && stream._writableState.finished;
  
    var onfinish = function onfinish() {
      writable = false;
      writableEnded = true;
      if (!readable) callback.call(stream);
    };
  
    var readableEnded = stream._readableState && stream._readableState.endEmitted;
  
    var onend = function onend() {
      readable = false;
      readableEnded = true;
      if (!writable) callback.call(stream);
    };
  
    var onerror = function onerror(err) {
      callback.call(stream, err);
    };
  
    var onclose = function onclose() {
      var err;
  
      if (readable && !readableEnded) {
        if (!stream._readableState || !stream._readableState.ended) err = new ERR_STREAM_PREMATURE_CLOSE();
        return callback.call(stream, err);
      }
  
      if (writable && !writableEnded) {
        if (!stream._writableState || !stream._writableState.ended) err = new ERR_STREAM_PREMATURE_CLOSE();
        return callback.call(stream, err);
      }
    };
  
    var onrequest = function onrequest() {
      stream.req.on('finish', onfinish);
    };
  
    if (isRequest(stream)) {
      stream.on('complete', onfinish);
      stream.on('abort', onclose);
      if (stream.req) onrequest();else stream.on('request', onrequest);
    } else if (writable && !stream._writableState) {
      // legacy streams
      stream.on('end', onlegacyfinish);
      stream.on('close', onlegacyfinish);
    }
  
    stream.on('end', onend);
    stream.on('finish', onfinish);
    if (opts.error !== false) stream.on('error', onerror);
    stream.on('close', onclose);
    return function () {
      stream.removeListener('complete', onfinish);
      stream.removeListener('abort', onclose);
      stream.removeListener('request', onrequest);
      if (stream.req) stream.req.removeListener('finish', onfinish);
      stream.removeListener('end', onlegacyfinish);
      stream.removeListener('close', onlegacyfinish);
      stream.removeListener('finish', onfinish);
      stream.removeListener('end', onend);
      stream.removeListener('error', onerror);
      stream.removeListener('close', onclose);
    };
  }
  
  module.exports = eos;
  },{"../../../errors":45}],55:[function(require,module,exports){
  module.exports = function () {
    throw new Error('Readable.from is not available in the browser')
  };
  
  },{}],56:[function(require,module,exports){
  // Ported from https://github.com/mafintosh/pump with
  // permission from the author, Mathias Buus (@mafintosh).
  'use strict';
  
  var eos;
  
  function once(callback) {
    var called = false;
    return function () {
      if (called) return;
      called = true;
      callback.apply(void 0, arguments);
    };
  }
  
  var _require$codes = require('../../../errors').codes,
      ERR_MISSING_ARGS = _require$codes.ERR_MISSING_ARGS,
      ERR_STREAM_DESTROYED = _require$codes.ERR_STREAM_DESTROYED;
  
  function noop(err) {
    // Rethrow the error if it exists to avoid swallowing it
    if (err) throw err;
  }
  
  function isRequest(stream) {
    return stream.setHeader && typeof stream.abort === 'function';
  }
  
  function destroyer(stream, reading, writing, callback) {
    callback = once(callback);
    var closed = false;
    stream.on('close', function () {
      closed = true;
    });
    if (eos === undefined) eos = require('./end-of-stream');
    eos(stream, {
      readable: reading,
      writable: writing
    }, function (err) {
      if (err) return callback(err);
      closed = true;
      callback();
    });
    var destroyed = false;
    return function (err) {
      if (closed) return;
      if (destroyed) return;
      destroyed = true; // request.destroy just do .end - .abort is what we want
  
      if (isRequest(stream)) return stream.abort();
      if (typeof stream.destroy === 'function') return stream.destroy();
      callback(err || new ERR_STREAM_DESTROYED('pipe'));
    };
  }
  
  function call(fn) {
    fn();
  }
  
  function pipe(from, to) {
    return from.pipe(to);
  }
  
  function popCallback(streams) {
    if (!streams.length) return noop;
    if (typeof streams[streams.length - 1] !== 'function') return noop;
    return streams.pop();
  }
  
  function pipeline() {
    for (var _len = arguments.length, streams = new Array(_len), _key = 0; _key < _len; _key++) {
      streams[_key] = arguments[_key];
    }
  
    var callback = popCallback(streams);
    if (Array.isArray(streams[0])) streams = streams[0];
  
    if (streams.length < 2) {
      throw new ERR_MISSING_ARGS('streams');
    }
  
    var error;
    var destroys = streams.map(function (stream, i) {
      var reading = i < streams.length - 1;
      var writing = i > 0;
      return destroyer(stream, reading, writing, function (err) {
        if (!error) error = err;
        if (err) destroys.forEach(call);
        if (reading) return;
        destroys.forEach(call);
        callback(error);
      });
    });
    return streams.reduce(pipe);
  }
  
  module.exports = pipeline;
  },{"../../../errors":45,"./end-of-stream":54}],57:[function(require,module,exports){
  'use strict';
  
  var ERR_INVALID_OPT_VALUE = require('../../../errors').codes.ERR_INVALID_OPT_VALUE;
  
  function highWaterMarkFrom(options, isDuplex, duplexKey) {
    return options.highWaterMark != null ? options.highWaterMark : isDuplex ? options[duplexKey] : null;
  }
  
  function getHighWaterMark(state, options, duplexKey, isDuplex) {
    var hwm = highWaterMarkFrom(options, isDuplex, duplexKey);
  
    if (hwm != null) {
      if (!(isFinite(hwm) && Math.floor(hwm) === hwm) || hwm < 0) {
        var name = isDuplex ? duplexKey : 'highWaterMark';
        throw new ERR_INVALID_OPT_VALUE(name, hwm);
      }
  
      return Math.floor(hwm);
    } // Default value
  
  
    return state.objectMode ? 16 : 16 * 1024;
  }
  
  module.exports = {
    getHighWaterMark: getHighWaterMark
  };
  },{"../../../errors":45}],58:[function(require,module,exports){
  arguments[4][24][0].apply(exports,arguments)
  },{"dup":24,"events":27}],59:[function(require,module,exports){
  exports = module.exports = require('./lib/_stream_readable.js');
  exports.Stream = exports;
  exports.Readable = exports;
  exports.Writable = require('./lib/_stream_writable.js');
  exports.Duplex = require('./lib/_stream_duplex.js');
  exports.Transform = require('./lib/_stream_transform.js');
  exports.PassThrough = require('./lib/_stream_passthrough.js');
  exports.finished = require('./lib/internal/streams/end-of-stream.js');
  exports.pipeline = require('./lib/internal/streams/pipeline.js');
  
  },{"./lib/_stream_duplex.js":46,"./lib/_stream_passthrough.js":47,"./lib/_stream_readable.js":48,"./lib/_stream_transform.js":49,"./lib/_stream_writable.js":50,"./lib/internal/streams/end-of-stream.js":54,"./lib/internal/streams/pipeline.js":56}],60:[function(require,module,exports){
  'use strict'
  
  function ReInterval (callback, interval, args) {
    var self = this;
  
    this._callback = callback;
    this._args = args;
  
    this._interval = setInterval(callback, interval, this._args);
  
    this.reschedule = function (interval) {
      // if no interval entered, use the interval passed in on creation
      if (!interval)
        interval = self._interval;
  
      if (self._interval)
        clearInterval(self._interval);
      self._interval = setInterval(self._callback, interval, self._args);
    };
  
    this.clear = function () {
      if (self._interval) {
        clearInterval(self._interval);
        self._interval = undefined;
      }
    };
    
    this.destroy = function () {
      if (self._interval) {
        clearInterval(self._interval);
      }
      self._callback = undefined;
      self._interval = undefined;
      self._args = undefined;
    };
  }
  
  function reInterval () {
    if (typeof arguments[0] !== 'function')
      throw new Error('callback needed');
    if (typeof arguments[1] !== 'number')
      throw new Error('interval needed');
  
    var args;
  
    if (arguments.length > 0) {
      args = new Array(arguments.length - 2);
  
      for (var i = 0; i < args.length; i++) {
        args[i] = arguments[i + 2];
      }
    }
  
    return new ReInterval(arguments[0], arguments[1], args);
  }
  
  module.exports = reInterval;
  
  },{}],61:[function(require,module,exports){
  /* eslint-disable node/no-deprecated-api */
  var buffer = require('buffer')
  var Buffer = buffer.Buffer
  
  // alternative to using Object.keys for old browsers
  function copyProps (src, dst) {
    for (var key in src) {
      dst[key] = src[key]
    }
  }
  if (Buffer.from && Buffer.alloc && Buffer.allocUnsafe && Buffer.allocUnsafeSlow) {
    module.exports = buffer
  } else {
    // Copy properties from require('buffer')
    copyProps(buffer, exports)
    exports.Buffer = SafeBuffer
  }
  
  function SafeBuffer (arg, encodingOrOffset, length) {
    return Buffer(arg, encodingOrOffset, length)
  }
  
  // Copy static methods from Buffer
  copyProps(Buffer, SafeBuffer)
  
  SafeBuffer.from = function (arg, encodingOrOffset, length) {
    if (typeof arg === 'number') {
      throw new TypeError('Argument must not be a number')
    }
    return Buffer(arg, encodingOrOffset, length)
  }
  
  SafeBuffer.alloc = function (size, fill, encoding) {
    if (typeof size !== 'number') {
      throw new TypeError('Argument must be a number')
    }
    var buf = Buffer(size)
    if (fill !== undefined) {
      if (typeof encoding === 'string') {
        buf.fill(fill, encoding)
      } else {
        buf.fill(fill)
      }
    } else {
      buf.fill(0)
    }
    return buf
  }
  
  SafeBuffer.allocUnsafe = function (size) {
    if (typeof size !== 'number') {
      throw new TypeError('Argument must be a number')
    }
    return Buffer(size)
  }
  
  SafeBuffer.allocUnsafeSlow = function (size) {
    if (typeof size !== 'number') {
      throw new TypeError('Argument must be a number')
    }
    return buffer.SlowBuffer(size)
  }
  
  },{"buffer":12}],62:[function(require,module,exports){
  module.exports = shift
  
  function shift (stream) {
    var rs = stream._readableState
    if (!rs) return null
    return (rs.objectMode || typeof stream._duplexState === 'number') ? stream.read() : stream.read(getStateLength(rs))
  }
  
  function getStateLength (state) {
    if (state.buffer.length) {
      // Since node 6.3.0 state.buffer is a BufferList not an array
      if (state.buffer.head) {
        return state.buffer.head.data.length
      }
  
      return state.buffer[0].length
    }
  
    return state.length
  }
  
  },{}],63:[function(require,module,exports){
  // Copyright Joyent, Inc. and other Node contributors.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a
  // copy of this software and associated documentation files (the
  // "Software"), to deal in the Software without restriction, including
  // without limitation the rights to use, copy, modify, merge, publish,
  // distribute, sublicense, and/or sell copies of the Software, and to permit
  // persons to whom the Software is furnished to do so, subject to the
  // following conditions:
  //
  // The above copyright notice and this permission notice shall be included
  // in all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
  // NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
  // DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  // USE OR OTHER DEALINGS IN THE SOFTWARE.
  
  'use strict';
  
  /*<replacement>*/
  
  var Buffer = require('safe-buffer').Buffer;
  /*</replacement>*/
  
  var isEncoding = Buffer.isEncoding || function (encoding) {
    encoding = '' + encoding;
    switch (encoding && encoding.toLowerCase()) {
      case 'hex':case 'utf8':case 'utf-8':case 'ascii':case 'binary':case 'base64':case 'ucs2':case 'ucs-2':case 'utf16le':case 'utf-16le':case 'raw':
        return true;
      default:
        return false;
    }
  };
  
  function _normalizeEncoding(enc) {
    if (!enc) return 'utf8';
    var retried;
    while (true) {
      switch (enc) {
        case 'utf8':
        case 'utf-8':
          return 'utf8';
        case 'ucs2':
        case 'ucs-2':
        case 'utf16le':
        case 'utf-16le':
          return 'utf16le';
        case 'latin1':
        case 'binary':
          return 'latin1';
        case 'base64':
        case 'ascii':
        case 'hex':
          return enc;
        default:
          if (retried) return; // undefined
          enc = ('' + enc).toLowerCase();
          retried = true;
      }
    }
  };
  
  // Do not cache `Buffer.isEncoding` when checking encoding names as some
  // modules monkey-patch it to support additional encodings
  function normalizeEncoding(enc) {
    var nenc = _normalizeEncoding(enc);
    if (typeof nenc !== 'string' && (Buffer.isEncoding === isEncoding || !isEncoding(enc))) throw new Error('Unknown encoding: ' + enc);
    return nenc || enc;
  }
  
  // StringDecoder provides an interface for efficiently splitting a series of
  // buffers into a series of JS strings without breaking apart multi-byte
  // characters.
  exports.StringDecoder = StringDecoder;
  function StringDecoder(encoding) {
    this.encoding = normalizeEncoding(encoding);
    var nb;
    switch (this.encoding) {
      case 'utf16le':
        this.text = utf16Text;
        this.end = utf16End;
        nb = 4;
        break;
      case 'utf8':
        this.fillLast = utf8FillLast;
        nb = 4;
        break;
      case 'base64':
        this.text = base64Text;
        this.end = base64End;
        nb = 3;
        break;
      default:
        this.write = simpleWrite;
        this.end = simpleEnd;
        return;
    }
    this.lastNeed = 0;
    this.lastTotal = 0;
    this.lastChar = Buffer.allocUnsafe(nb);
  }
  
  StringDecoder.prototype.write = function (buf) {
    if (buf.length === 0) return '';
    var r;
    var i;
    if (this.lastNeed) {
      r = this.fillLast(buf);
      if (r === undefined) return '';
      i = this.lastNeed;
      this.lastNeed = 0;
    } else {
      i = 0;
    }
    if (i < buf.length) return r ? r + this.text(buf, i) : this.text(buf, i);
    return r || '';
  };
  
  StringDecoder.prototype.end = utf8End;
  
  // Returns only complete characters in a Buffer
  StringDecoder.prototype.text = utf8Text;
  
  // Attempts to complete a partial non-UTF-8 character using bytes from a Buffer
  StringDecoder.prototype.fillLast = function (buf) {
    if (this.lastNeed <= buf.length) {
      buf.copy(this.lastChar, this.lastTotal - this.lastNeed, 0, this.lastNeed);
      return this.lastChar.toString(this.encoding, 0, this.lastTotal);
    }
    buf.copy(this.lastChar, this.lastTotal - this.lastNeed, 0, buf.length);
    this.lastNeed -= buf.length;
  };
  
  // Checks the type of a UTF-8 byte, whether it's ASCII, a leading byte, or a
  // continuation byte. If an invalid byte is detected, -2 is returned.
  function utf8CheckByte(byte) {
    if (byte <= 0x7F) return 0;else if (byte >> 5 === 0x06) return 2;else if (byte >> 4 === 0x0E) return 3;else if (byte >> 3 === 0x1E) return 4;
    return byte >> 6 === 0x02 ? -1 : -2;
  }
  
  // Checks at most 3 bytes at the end of a Buffer in order to detect an
  // incomplete multi-byte UTF-8 character. The total number of bytes (2, 3, or 4)
  // needed to complete the UTF-8 character (if applicable) are returned.
  function utf8CheckIncomplete(self, buf, i) {
    var j = buf.length - 1;
    if (j < i) return 0;
    var nb = utf8CheckByte(buf[j]);
    if (nb >= 0) {
      if (nb > 0) self.lastNeed = nb - 1;
      return nb;
    }
    if (--j < i || nb === -2) return 0;
    nb = utf8CheckByte(buf[j]);
    if (nb >= 0) {
      if (nb > 0) self.lastNeed = nb - 2;
      return nb;
    }
    if (--j < i || nb === -2) return 0;
    nb = utf8CheckByte(buf[j]);
    if (nb >= 0) {
      if (nb > 0) {
        if (nb === 2) nb = 0;else self.lastNeed = nb - 3;
      }
      return nb;
    }
    return 0;
  }
  
  // Validates as many continuation bytes for a multi-byte UTF-8 character as
  // needed or are available. If we see a non-continuation byte where we expect
  // one, we "replace" the validated continuation bytes we've seen so far with
  // a single UTF-8 replacement character ('\ufffd'), to match v8's UTF-8 decoding
  // behavior. The continuation byte check is included three times in the case
  // where all of the continuation bytes for a character exist in the same buffer.
  // It is also done this way as a slight performance increase instead of using a
  // loop.
  function utf8CheckExtraBytes(self, buf, p) {
    if ((buf[0] & 0xC0) !== 0x80) {
      self.lastNeed = 0;
      return '\ufffd';
    }
    if (self.lastNeed > 1 && buf.length > 1) {
      if ((buf[1] & 0xC0) !== 0x80) {
        self.lastNeed = 1;
        return '\ufffd';
      }
      if (self.lastNeed > 2 && buf.length > 2) {
        if ((buf[2] & 0xC0) !== 0x80) {
          self.lastNeed = 2;
          return '\ufffd';
        }
      }
    }
  }
  
  // Attempts to complete a multi-byte UTF-8 character using bytes from a Buffer.
  function utf8FillLast(buf) {
    var p = this.lastTotal - this.lastNeed;
    var r = utf8CheckExtraBytes(this, buf, p);
    if (r !== undefined) return r;
    if (this.lastNeed <= buf.length) {
      buf.copy(this.lastChar, p, 0, this.lastNeed);
      return this.lastChar.toString(this.encoding, 0, this.lastTotal);
    }
    buf.copy(this.lastChar, p, 0, buf.length);
    this.lastNeed -= buf.length;
  }
  
  // Returns all complete UTF-8 characters in a Buffer. If the Buffer ended on a
  // partial character, the character's bytes are buffered until the required
  // number of bytes are available.
  function utf8Text(buf, i) {
    var total = utf8CheckIncomplete(this, buf, i);
    if (!this.lastNeed) return buf.toString('utf8', i);
    this.lastTotal = total;
    var end = buf.length - (total - this.lastNeed);
    buf.copy(this.lastChar, 0, end);
    return buf.toString('utf8', i, end);
  }
  
  // For UTF-8, a replacement character is added when ending on a partial
  // character.
  function utf8End(buf) {
    var r = buf && buf.length ? this.write(buf) : '';
    if (this.lastNeed) return r + '\ufffd';
    return r;
  }
  
  // UTF-16LE typically needs two bytes per character, but even if we have an even
  // number of bytes available, we need to check if we end on a leading/high
  // surrogate. In that case, we need to wait for the next two bytes in order to
  // decode the last character properly.
  function utf16Text(buf, i) {
    if ((buf.length - i) % 2 === 0) {
      var r = buf.toString('utf16le', i);
      if (r) {
        var c = r.charCodeAt(r.length - 1);
        if (c >= 0xD800 && c <= 0xDBFF) {
          this.lastNeed = 2;
          this.lastTotal = 4;
          this.lastChar[0] = buf[buf.length - 2];
          this.lastChar[1] = buf[buf.length - 1];
          return r.slice(0, -1);
        }
      }
      return r;
    }
    this.lastNeed = 1;
    this.lastTotal = 2;
    this.lastChar[0] = buf[buf.length - 1];
    return buf.toString('utf16le', i, buf.length - 1);
  }
  
  // For UTF-16LE we do not explicitly append special replacement characters if we
  // end on a partial character, we simply let v8 handle that.
  function utf16End(buf) {
    var r = buf && buf.length ? this.write(buf) : '';
    if (this.lastNeed) {
      var end = this.lastTotal - this.lastNeed;
      return r + this.lastChar.toString('utf16le', 0, end);
    }
    return r;
  }
  
  function base64Text(buf, i) {
    var n = (buf.length - i) % 3;
    if (n === 0) return buf.toString('base64', i);
    this.lastNeed = 3 - n;
    this.lastTotal = 3;
    if (n === 1) {
      this.lastChar[0] = buf[buf.length - 1];
    } else {
      this.lastChar[0] = buf[buf.length - 2];
      this.lastChar[1] = buf[buf.length - 1];
    }
    return buf.toString('base64', i, buf.length - n);
  }
  
  function base64End(buf) {
    var r = buf && buf.length ? this.write(buf) : '';
    if (this.lastNeed) return r + this.lastChar.toString('base64', 0, 3 - this.lastNeed);
    return r;
  }
  
  // Pass bytes on through for single-byte encodings (e.g. ascii, latin1, hex)
  function simpleWrite(buf) {
    return buf.toString(this.encoding);
  }
  
  function simpleEnd(buf) {
    return buf && buf.length ? this.write(buf) : '';
  }
  },{"safe-buffer":61}],64:[function(require,module,exports){
  (function (setImmediate,clearImmediate){
  var nextTick = require('process/browser.js').nextTick;
  var apply = Function.prototype.apply;
  var slice = Array.prototype.slice;
  var immediateIds = {};
  var nextImmediateId = 0;
  
  // DOM APIs, for completeness
  
  exports.setTimeout = function() {
    return new Timeout(apply.call(setTimeout, window, arguments), clearTimeout);
  };
  exports.setInterval = function() {
    return new Timeout(apply.call(setInterval, window, arguments), clearInterval);
  };
  exports.clearTimeout =
  exports.clearInterval = function(timeout) { timeout.close(); };
  
  function Timeout(id, clearFn) {
    this._id = id;
    this._clearFn = clearFn;
  }
  Timeout.prototype.unref = Timeout.prototype.ref = function() {};
  Timeout.prototype.close = function() {
    this._clearFn.call(window, this._id);
  };
  
  // Does not start the time, just sets up the members needed.
  exports.enroll = function(item, msecs) {
    clearTimeout(item._idleTimeoutId);
    item._idleTimeout = msecs;
  };
  
  exports.unenroll = function(item) {
    clearTimeout(item._idleTimeoutId);
    item._idleTimeout = -1;
  };
  
  exports._unrefActive = exports.active = function(item) {
    clearTimeout(item._idleTimeoutId);
  
    var msecs = item._idleTimeout;
    if (msecs >= 0) {
      item._idleTimeoutId = setTimeout(function onTimeout() {
        if (item._onTimeout)
          item._onTimeout();
      }, msecs);
    }
  };
  
  // That's not how node.js implements it but the exposed api is the same.
  exports.setImmediate = typeof setImmediate === "function" ? setImmediate : function(fn) {
    var id = nextImmediateId++;
    var args = arguments.length < 2 ? false : slice.call(arguments, 1);
  
    immediateIds[id] = true;
  
    nextTick(function onNextTick() {
      if (immediateIds[id]) {
        // fn.call() is faster so we optimize for the common use-case
        // @see http://jsperf.com/call-apply-segu
        if (args) {
          fn.apply(null, args);
        } else {
          fn.call(null);
        }
        // Prevent ids from leaking
        exports.clearImmediate(id);
      }
    });
  
    return id;
  };
  
  exports.clearImmediate = typeof clearImmediate === "function" ? clearImmediate : function(id) {
    delete immediateIds[id];
  };
  }).call(this,require("timers").setImmediate,require("timers").clearImmediate)
  },{"process/browser.js":44,"timers":64}],65:[function(require,module,exports){
  (function (global){
  
  /**
   * Module exports.
   */
  
  module.exports = deprecate;
  
  /**
   * Mark that a method should not be used.
   * Returns a modified function which warns once by default.
   *
   * If `localStorage.noDeprecation = true` is set, then it is a no-op.
   *
   * If `localStorage.throwDeprecation = true` is set, then deprecated functions
   * will throw an Error when invoked.
   *
   * If `localStorage.traceDeprecation = true` is set, then deprecated functions
   * will invoke `console.trace()` instead of `console.error()`.
   *
   * @param {Function} fn - the function to deprecate
   * @param {String} msg - the string to print to the console when `fn` is invoked
   * @returns {Function} a new "deprecated" version of `fn`
   * @api public
   */
  
  function deprecate (fn, msg) {
    if (config('noDeprecation')) {
      return fn;
    }
  
    var warned = false;
    function deprecated() {
      if (!warned) {
        if (config('throwDeprecation')) {
          throw new Error(msg);
        } else if (config('traceDeprecation')) {
          console.trace(msg);
        } else {
          console.warn(msg);
        }
        warned = true;
      }
      return fn.apply(this, arguments);
    }
  
    return deprecated;
  }
  
  /**
   * Checks `localStorage` for boolean values for the given `name`.
   *
   * @param {String} name
   * @returns {Boolean}
   * @api private
   */
  
  function config (name) {
    // accessing global.localStorage can trigger a DOMException in sandboxed iframes
    try {
      if (!global.localStorage) return false;
    } catch (_) {
      return false;
    }
    var val = global.localStorage[name];
    if (null == val) return false;
    return String(val).toLowerCase() === 'true';
  }
  
  }).call(this,typeof global !== "undefined" ? global : typeof self !== "undefined" ? self : typeof window !== "undefined" ? window : {})
  },{}],66:[function(require,module,exports){
  // Returns a wrapper function that returns a wrapped callback
  // The wrapper function should do some stuff, and return a
  // presumably different callback function.
  // This makes sure that own properties are retained, so that
  // decorations and such are not lost along the way.
  module.exports = wrappy
  function wrappy (fn, cb) {
    if (fn && cb) return wrappy(fn)(cb)
  
    if (typeof fn !== 'function')
      throw new TypeError('need wrapper function')
  
    Object.keys(fn).forEach(function (k) {
      wrapper[k] = fn[k]
    })
  
    return wrapper
  
    function wrapper() {
      var args = new Array(arguments.length)
      for (var i = 0; i < args.length; i++) {
        args[i] = arguments[i]
      }
      var ret = fn.apply(this, args)
      var cb = args[args.length-1]
      if (typeof ret === 'function' && ret !== cb) {
        Object.keys(cb).forEach(function (k) {
          ret[k] = cb[k]
        })
      }
      return ret
    }
  }
  
  },{}],67:[function(require,module,exports){
  'use strict';
  
  module.exports = function () {
    throw new Error(
      'ws does not work in the browser. Browser clients must use the native ' +
        'WebSocket object'
    );
  };
  
  },{}],68:[function(require,module,exports){
  module.exports = extend
  
  var hasOwnProperty = Object.prototype.hasOwnProperty;
  
  function extend() {
      var target = {}
  
      for (var i = 0; i < arguments.length; i++) {
          var source = arguments[i]
  
          for (var key in source) {
              if (hasOwnProperty.call(source, key)) {
                  target[key] = source[key]
              }
          }
      }
  
      return target
  }
  
  },{}]},{},[9])(9)
  });
  