text: 'use strict';
  
  var domain;
  
  // This constructor is used to store event handlers. Instantiating this is
  // faster than explicitly calling `Object.create(null)` to get a "clean" empty
  // object (tested with v8 v4.9).
  function EventHandlers() {}
  EventHandlers.prototype = Object.create(null);
  
  function EventEmitter() {
    EventEmitter.init.call(this);
  }
  export default EventEmitter;
  export {EventEmitter};
  
  // nodejs oddity
  // require('events') === require('events').EventEmitter
  EventEmitter.EventEmitter = EventEmitter
  
  EventEmitter.usingDomains = false;
  
  EventEmitter.prototype.domain = undefined;
  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.
  EventEmitter.defaultMaxListeners = 10;
  
  EventEmitter.init = function() {
    this.domain = null;
    if (EventEmitter.usingDomains) {
      // if there is an active domain, then attach to it.
      if (domain.active && !(this instanceof domain.Domain)) {
        this.domain = domain.active;
      }
    }
  
    if (!this._events || this._events === Object.getPrototypeOf(this)._events) {
      this._events = new EventHandlers();
      this._eventsCount = 0;
    }
  
    this._maxListeners = this._maxListeners || undefined;
  };
  
  // 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, domain;
    var needDomainExit = false;
    var doError = (type === 'error');
  
    events = this._events;
    if (events)
      doError = (doError && events.error == null);
    else if (!doError)
      return false;
  
    domain = this.domain;
  
    // If there is no 'error' event listener then throw.
    if (doError) {
      er = arguments[1];
      if (domain) {
        if (!er)
          er = new Error('Uncaught, unspecified "error" event');
        er.domainEmitter = this;
        er.domain = domain;
        er.domainThrown = false;
        domain.emit('error', er);
      } else if (er instanceof Error) {
        throw er; // Unhandled 'error' event
      } else {
        // At least give some kind of context to the user
        var err = new Error('Uncaught, unspecified "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);
    }
  
    if (needDomainExit)
      domain.exit();
  
    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 = new EventHandlers();
      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 + ' ' + type + ' listeners added. ' +
                              'Use emitter.setMaxListeners() to increase limit');
          w.name = 'MaxListenersExceededWarning';
          w.emitter = target;
          w.type = type;
          w.count = existing.length;
          emitWarning(w);
        }
      }
    }
  
    return target;
  }
  function emitWarning(e) {
    typeof console.warn === 'function' ? console.warn(e) : console.log(e);
  }
  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 _onceWrap(target, type, listener) {
    var fired = false;
    function g() {
      target.removeListener(type, g);
      if (!fired) {
        fired = true;
        listener.apply(target, arguments);
      }
    }
    g.listener = listener;
    return g;
  }
  
  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 iff 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 && list.listener === listener)) {
          if (--this._eventsCount === 0)
            this._events = new EventHandlers();
          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; i-- > 0;) {
            if (list[i] === listener ||
                (list[i].listener && list[i].listener === listener)) {
              originalListener = list[i].listener;
              position = i;
              break;
            }
          }
  
          if (position < 0)
            return this;
  
          if (list.length === 1) {
            list[0] = undefined;
            if (--this._eventsCount === 0) {
              this._events = new EventHandlers();
              return this;
            } else {
              delete events[type];
            }
          } else {
            spliceOne(list, position);
          }
  
          if (events.removeListener)
            this.emit('removeListener', type, originalListener || listener);
        }
  
        return this;
      };
      
  // Alias for removeListener added in NodeJS 10.0
  // https://nodejs.org/api/events.html#events_emitter_off_eventname_listener
  EventEmitter.prototype.off = function(type, listener){
      return this.removeListener(type, listener);
  };
  
  EventEmitter.prototype.removeAllListeners =
      function removeAllListeners(type) {
        var listeners, events;
  
        events = this._events;
        if (!events)
          return this;
  
        // not listening for removeListener, no need to emit
        if (!events.removeListener) {
          if (arguments.length === 0) {
            this._events = new EventHandlers();
            this._eventsCount = 0;
          } else if (events[type]) {
            if (--this._eventsCount === 0)
              this._events = new EventHandlers();
            else
              delete events[type];
          }
          return this;
        }
  
        // emit removeListener for all listeners on all events
        if (arguments.length === 0) {
          var keys = Object.keys(events);
          for (var i = 0, key; i < keys.length; ++i) {
            key = keys[i];
            if (key === 'removeListener') continue;
            this.removeAllListeners(key);
          }
          this.removeAllListeners('removeListener');
          this._events = new EventHandlers();
          this._eventsCount = 0;
          return this;
        }
  
        listeners = events[type];
  
        if (typeof listeners === 'function') {
          this.removeListener(type, listeners);
        } else if (listeners) {
          // LIFO order
          do {
            this.removeListener(type, listeners[listeners.length - 1]);
          } while (listeners[0]);
        }
  
        return this;
      };
  
  EventEmitter.prototype.listeners = function listeners(type) {
    var evlistener;
    var ret;
    var events = this._events;
  
    if (!events)
      ret = [];
    else {
      evlistener = events[type];
      if (!evlistener)
        ret = [];
      else if (typeof evlistener === 'function')
        ret = [evlistener.listener || evlistener];
      else
        ret = unwrapListeners(evlistener);
    }
  
    return ret;
  };
  
  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, i) {
    var copy = new Array(i);
    while (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;
  }
  