text: 'use strict'
  
  // an async function fails early in Node.js versions prior to 8.
  async function requiresNode8OrGreater () {}
  requiresNode8OrGreater()
  
  const argsert = require('./lib/argsert')
  const fs = require('fs')
  const Command = require('./lib/command')
  const Completion = require('./lib/completion')
  const Parser = require('yargs-parser')
  const path = require('path')
  const Usage = require('./lib/usage')
  const Validation = require('./lib/validation')
  const Y18n = require('y18n')
  const objFilter = require('./lib/obj-filter')
  const setBlocking = require('set-blocking')
  const applyExtends = require('./lib/apply-extends')
  const { globalMiddlewareFactory } = require('./lib/middleware')
  const YError = require('./lib/yerror')
  
  exports = module.exports = Yargs
  function Yargs (processArgs, cwd, parentRequire) {
    processArgs = processArgs || [] // handle calling yargs().
  
    const self = {}
    let command = null
    let completion = null
    let groups = {}
    let globalMiddleware = []
    let output = ''
    let preservedGroups = {}
    let usage = null
    let validation = null
  
    const y18n = Y18n({
      directory: path.resolve(__dirname, './locales'),
      updateFiles: false
    })
  
    self.middleware = globalMiddlewareFactory(globalMiddleware, self)
  
    if (!cwd) cwd = process.cwd()
  
    self.scriptName = function (scriptName) {
      self.customScriptName = true
      self.$0 = scriptName
      return self
    }
  
    // ignore the node bin, specify this in your
    // bin file with #!/usr/bin/env node
    if (/\b(node|iojs|electron)(\.exe)?$/.test(process.argv[0])) {
      self.$0 = process.argv.slice(1, 2)
    } else {
      self.$0 = process.argv.slice(0, 1)
    }
  
    self.$0 = self.$0
      .map((x, i) => {
        const b = rebase(cwd, x)
        return x.match(/^(\/|([a-zA-Z]:)?\\)/) && b.length < x.length ? b : x
      })
      .join(' ').trim()
  
    if (process.env._ !== undefined && process.argv[1] === process.env._) {
      self.$0 = process.env._.replace(
        `${path.dirname(process.execPath)}/`, ''
      )
    }
  
    // use context object to keep track of resets, subcommand execution, etc
    // submodules should modify and check the state of context as necessary
    const context = { resets: -1, commands: [], fullCommands: [], files: [] }
    self.getContext = () => context
  
    // puts yargs back into an initial state. any keys
    // that have been set to "global" will not be reset
    // by this action.
    let options
    self.resetOptions = self.reset = function resetOptions (aliases) {
      context.resets++
      aliases = aliases || {}
      options = options || {}
      // put yargs back into an initial state, this
      // logic is used to build a nested command
      // hierarchy.
      const tmpOptions = {}
      tmpOptions.local = options.local ? options.local : []
      tmpOptions.configObjects = options.configObjects ? options.configObjects : []
  
      // if a key has been explicitly set as local,
      // we should reset it before passing options to command.
      const localLookup = {}
      tmpOptions.local.forEach((l) => {
        localLookup[l] = true
        ;(aliases[l] || []).forEach((a) => {
          localLookup[a] = true
        })
      })
  
      // add all groups not set to local to preserved groups
      Object.assign(
        preservedGroups,
        Object.keys(groups).reduce((acc, groupName) => {
          const keys = groups[groupName].filter(key => !(key in localLookup))
          if (keys.length > 0) {
            acc[groupName] = keys
          }
          return acc
        }, {})
      )
      // groups can now be reset
      groups = {}
  
      const arrayOptions = [
        'array', 'boolean', 'string', 'skipValidation',
        'count', 'normalize', 'number',
        'hiddenOptions'
      ]
  
      const objectOptions = [
        'narg', 'key', 'alias', 'default', 'defaultDescription',
        'config', 'choices', 'demandedOptions', 'demandedCommands', 'coerce'
      ]
  
      arrayOptions.forEach((k) => {
        tmpOptions[k] = (options[k] || []).filter(k => !localLookup[k])
      })
  
      objectOptions.forEach((k) => {
        tmpOptions[k] = objFilter(options[k], (k, v) => !localLookup[k])
      })
  
      tmpOptions.envPrefix = options.envPrefix
      options = tmpOptions
  
      // if this is the first time being executed, create
      // instances of all our helpers -- otherwise just reset.
      usage = usage ? usage.reset(localLookup) : Usage(self, y18n)
      validation = validation ? validation.reset(localLookup) : Validation(self, usage, y18n)
      command = command ? command.reset() : Command(self, usage, validation, globalMiddleware)
      if (!completion) completion = Completion(self, usage, command)
  
      completionCommand = null
      output = ''
      exitError = null
      hasOutput = false
      self.parsed = false
  
      return self
    }
    self.resetOptions()
  
    // temporary hack: allow "freezing" of reset-able state for parse(msg, cb)
    let frozens = []
    function freeze () {
      let frozen = {}
      frozens.push(frozen)
      frozen.options = options
      frozen.configObjects = options.configObjects.slice(0)
      frozen.exitProcess = exitProcess
      frozen.groups = groups
      usage.freeze()
      validation.freeze()
      command.freeze()
      frozen.strict = strict
      frozen.completionCommand = completionCommand
      frozen.output = output
      frozen.exitError = exitError
      frozen.hasOutput = hasOutput
      frozen.parsed = self.parsed
      frozen.parseFn = parseFn
      frozen.parseContext = parseContext
    }
    function unfreeze () {
      let frozen = frozens.pop()
      options = frozen.options
      options.configObjects = frozen.configObjects
      exitProcess = frozen.exitProcess
      groups = frozen.groups
      output = frozen.output
      exitError = frozen.exitError
      hasOutput = frozen.hasOutput
      self.parsed = frozen.parsed
      usage.unfreeze()
      validation.unfreeze()
      command.unfreeze()
      strict = frozen.strict
      completionCommand = frozen.completionCommand
      parseFn = frozen.parseFn
      parseContext = frozen.parseContext
    }
  
    self.boolean = function (keys) {
      argsert('<array|string>', [keys], arguments.length)
      populateParserHintArray('boolean', keys)
      return self
    }
  
    self.array = function (keys) {
      argsert('<array|string>', [keys], arguments.length)
      populateParserHintArray('array', keys)
      return self
    }
  
    self.number = function (keys) {
      argsert('<array|string>', [keys], arguments.length)
      populateParserHintArray('number', keys)
      return self
    }
  
    self.normalize = function (keys) {
      argsert('<array|string>', [keys], arguments.length)
      populateParserHintArray('normalize', keys)
      return self
    }
  
    self.count = function (keys) {
      argsert('<array|string>', [keys], arguments.length)
      populateParserHintArray('count', keys)
      return self
    }
  
    self.string = function (keys) {
      argsert('<array|string>', [keys], arguments.length)
      populateParserHintArray('string', keys)
      return self
    }
  
    self.requiresArg = function (keys) {
      argsert('<array|string>', [keys], arguments.length)
      populateParserHintObject(self.nargs, false, 'narg', keys, 1)
      return self
    }
  
    self.skipValidation = function (keys) {
      argsert('<array|string>', [keys], arguments.length)
      populateParserHintArray('skipValidation', keys)
      return self
    }
  
    function populateParserHintArray (type, keys, value) {
      keys = [].concat(keys)
      keys.forEach((key) => {
        options[type].push(key)
      })
    }
  
    self.nargs = function (key, value) {
      argsert('<string|object|array> [number]', [key, value], arguments.length)
      populateParserHintObject(self.nargs, false, 'narg', key, value)
      return self
    }
  
    self.choices = function (key, value) {
      argsert('<object|string|array> [string|array]', [key, value], arguments.length)
      populateParserHintObject(self.choices, true, 'choices', key, value)
      return self
    }
  
    self.alias = function (key, value) {
      argsert('<object|string|array> [string|array]', [key, value], arguments.length)
      populateParserHintObject(self.alias, true, 'alias', key, value)
      return self
    }
  
    // TODO: actually deprecate self.defaults.
    self.default = self.defaults = function (key, value, defaultDescription) {
      argsert('<object|string|array> [*] [string]', [key, value, defaultDescription], arguments.length)
      if (defaultDescription) options.defaultDescription[key] = defaultDescription
      if (typeof value === 'function') {
        if (!options.defaultDescription[key]) options.defaultDescription[key] = usage.functionDescription(value)
        value = value.call()
      }
      populateParserHintObject(self.default, false, 'default', key, value)
      return self
    }
  
    self.describe = function (key, desc) {
      argsert('<object|string|array> [string]', [key, desc], arguments.length)
      populateParserHintObject(self.describe, false, 'key', key, true)
      usage.describe(key, desc)
      return self
    }
  
    self.demandOption = function (keys, msg) {
      argsert('<object|string|array> [string]', [keys, msg], arguments.length)
      populateParserHintObject(self.demandOption, false, 'demandedOptions', keys, msg)
      return self
    }
  
    self.coerce = function (keys, value) {
      argsert('<object|string|array> [function]', [keys, value], arguments.length)
      populateParserHintObject(self.coerce, false, 'coerce', keys, value)
      return self
    }
  
    function populateParserHintObject (builder, isArray, type, key, value) {
      if (Array.isArray(key)) {
        // an array of keys with one value ['x', 'y', 'z'], function parse () {}
        const temp = {}
        key.forEach((k) => {
          temp[k] = value
        })
        builder(temp)
      } else if (typeof key === 'object') {
        // an object of key value pairs: {'x': parse () {}, 'y': parse() {}}
        Object.keys(key).forEach((k) => {
          builder(k, key[k])
        })
      } else {
        // a single key value pair 'x', parse() {}
        if (isArray) {
          options[type][key] = (options[type][key] || []).concat(value)
        } else {
          options[type][key] = value
        }
      }
    }
  
    function deleteFromParserHintObject (optionKey) {
      // delete from all parsing hints:
      // boolean, array, key, alias, etc.
      Object.keys(options).forEach((hintKey) => {
        const hint = options[hintKey]
        if (Array.isArray(hint)) {
          if (~hint.indexOf(optionKey)) hint.splice(hint.indexOf(optionKey), 1)
        } else if (typeof hint === 'object') {
          delete hint[optionKey]
        }
      })
      // now delete the description from usage.js.
      delete usage.getDescriptions()[optionKey]
    }
  
    self.config = function config (key, msg, parseFn) {
      argsert('[object|string] [string|function] [function]', [key, msg, parseFn], arguments.length)
      // allow a config object to be provided directly.
      if (typeof key === 'object') {
        key = applyExtends(key, cwd, self.getParserConfiguration()['deep-merge-config'])
        options.configObjects = (options.configObjects || []).concat(key)
        return self
      }
  
      // allow for a custom parsing function.
      if (typeof msg === 'function') {
        parseFn = msg
        msg = null
      }
  
      key = key || 'config'
      self.describe(key, msg || usage.deferY18nLookup('Path to JSON config file'))
      ;(Array.isArray(key) ? key : [key]).forEach((k) => {
        options.config[k] = parseFn || true
      })
  
      return self
    }
  
    self.example = function (cmd, description) {
      argsert('<string> [string]', [cmd, description], arguments.length)
      usage.example(cmd, description)
      return self
    }
  
    self.command = function (cmd, description, builder, handler, middlewares) {
      argsert('<string|array|object> [string|boolean] [function|object] [function] [array]', [cmd, description, builder, handler, middlewares], arguments.length)
      command.addHandler(cmd, description, builder, handler, middlewares)
      return self
    }
  
    self.commandDir = function (dir, opts) {
      argsert('<string> [object]', [dir, opts], arguments.length)
      const req = parentRequire || require
      command.addDirectory(dir, self.getContext(), req, require('get-caller-file')(), opts)
      return self
    }
  
    // TODO: deprecate self.demand in favor of
    // .demandCommand() .demandOption().
    self.demand = self.required = self.require = function demand (keys, max, msg) {
      // you can optionally provide a 'max' key,
      // which will raise an exception if too many '_'
      // options are provided.
      if (Array.isArray(max)) {
        max.forEach((key) => {
          self.demandOption(key, msg)
        })
        max = Infinity
      } else if (typeof max !== 'number') {
        msg = max
        max = Infinity
      }
  
      if (typeof keys === 'number') {
        self.demandCommand(keys, max, msg, msg)
      } else if (Array.isArray(keys)) {
        keys.forEach((key) => {
          self.demandOption(key, msg)
        })
      } else {
        if (typeof msg === 'string') {
          self.demandOption(keys, msg)
        } else if (msg === true || typeof msg === 'undefined') {
          self.demandOption(keys)
        }
      }
  
      return self
    }
  
    self.demandCommand = function demandCommand (min, max, minMsg, maxMsg) {
      argsert('[number] [number|string] [string|null|undefined] [string|null|undefined]', [min, max, minMsg, maxMsg], arguments.length)
  
      if (typeof min === 'undefined') min = 1
  
      if (typeof max !== 'number') {
        minMsg = max
        max = Infinity
      }
  
      self.global('_', false)
  
      options.demandedCommands._ = {
        min,
        max,
        minMsg,
        maxMsg
      }
  
      return self
    }
  
    self.getDemandedOptions = () => {
      argsert([], 0)
      return options.demandedOptions
    }
  
    self.getDemandedCommands = () => {
      argsert([], 0)
      return options.demandedCommands
    }
  
    self.implies = function (key, value) {
      argsert('<string|object> [number|string|array]', [key, value], arguments.length)
      validation.implies(key, value)
      return self
    }
  
    self.conflicts = function (key1, key2) {
      argsert('<string|object> [string|array]', [key1, key2], arguments.length)
      validation.conflicts(key1, key2)
      return self
    }
  
    self.usage = function (msg, description, builder, handler) {
      argsert('<string|null|undefined> [string|boolean] [function|object] [function]', [msg, description, builder, handler], arguments.length)
  
      if (description !== undefined) {
        // .usage() can be used as an alias for defining
        // a default command.
        if ((msg || '').match(/^\$0( |$)/)) {
          return self.command(msg, description, builder, handler)
        } else {
          throw new YError('.usage() description must start with $0 if being used as alias for .command()')
        }
      } else {
        usage.usage(msg)
        return self
      }
    }
  
    self.epilogue = self.epilog = function (msg) {
      argsert('<string>', [msg], arguments.length)
      usage.epilog(msg)
      return self
    }
  
    self.fail = function (f) {
      argsert('<function>', [f], arguments.length)
      usage.failFn(f)
      return self
    }
  
    self.check = function (f, _global) {
      argsert('<function> [boolean]', [f, _global], arguments.length)
      validation.check(f, _global !== false)
      return self
    }
  
    self.global = function global (globals, global) {
      argsert('<string|array> [boolean]', [globals, global], arguments.length)
      globals = [].concat(globals)
      if (global !== false) {
        options.local = options.local.filter(l => globals.indexOf(l) === -1)
      } else {
        globals.forEach((g) => {
          if (options.local.indexOf(g) === -1) options.local.push(g)
        })
      }
      return self
    }
  
    self.pkgConf = function pkgConf (key, rootPath) {
      argsert('<string> [string]', [key, rootPath], arguments.length)
      let conf = null
      // prefer cwd to require-main-filename in this method
      // since we're looking for e.g. "nyc" config in nyc consumer
      // rather than "yargs" config in nyc (where nyc is the main filename)
      const obj = pkgUp(rootPath || cwd)
  
      // If an object exists in the key, add it to options.configObjects
      if (obj[key] && typeof obj[key] === 'object') {
        conf = applyExtends(obj[key], rootPath || cwd, self.getParserConfiguration()['deep-merge-config'])
        options.configObjects = (options.configObjects || []).concat(conf)
      }
  
      return self
    }
  
    const pkgs = {}
    function pkgUp (rootPath) {
      const npath = rootPath || '*'
      if (pkgs[npath]) return pkgs[npath]
      const findUp = require('find-up')
  
      let obj = {}
      try {
        let startDir = rootPath || require('require-main-filename')(parentRequire || require)
  
        // When called in an environment that lacks require.main.filename, such as a jest test runner,
        // startDir is already process.cwd(), and should not be shortened.
        // Whether or not it is _actually_ a directory (e.g., extensionless bin) is irrelevant, find-up handles it.
        if (!rootPath && path.extname(startDir)) {
          startDir = path.dirname(startDir)
        }
  
        const pkgJsonPath = findUp.sync('package.json', {
          cwd: startDir
        })
        obj = JSON.parse(fs.readFileSync(pkgJsonPath))
      } catch (noop) {}
  
      pkgs[npath] = obj || {}
      return pkgs[npath]
    }
  
    let parseFn = null
    let parseContext = null
    self.parse = function parse (args, shortCircuit, _parseFn) {
      argsert('[string|array] [function|boolean|object] [function]', [args, shortCircuit, _parseFn], arguments.length)
      freeze()
      if (typeof args === 'undefined') {
        const argv = self._parseArgs(processArgs)
        const tmpParsed = self.parsed
        unfreeze()
        // TODO: remove this compatibility hack when we release yargs@15.x:
        self.parsed = tmpParsed
        return argv
      }
  
      // a context object can optionally be provided, this allows
      // additional information to be passed to a command handler.
      if (typeof shortCircuit === 'object') {
        parseContext = shortCircuit
        shortCircuit = _parseFn
      }
  
      // by providing a function as a second argument to
      // parse you can capture output that would otherwise
      // default to printing to stdout/stderr.
      if (typeof shortCircuit === 'function') {
        parseFn = shortCircuit
        shortCircuit = null
      }
      // completion short-circuits the parsing process,
      // skipping validation, etc.
      if (!shortCircuit) processArgs = args
  
      if (parseFn) exitProcess = false
  
      const parsed = self._parseArgs(args, shortCircuit)
      if (parseFn) parseFn(exitError, parsed, output)
      unfreeze()
  
      return parsed
    }
  
    self._getParseContext = () => parseContext || {}
  
    self._hasParseCallback = () => !!parseFn
  
    self.option = self.options = function option (key, opt) {
      argsert('<string|object> [object]', [key, opt], arguments.length)
      if (typeof key === 'object') {
        Object.keys(key).forEach((k) => {
          self.options(k, key[k])
        })
      } else {
        if (typeof opt !== 'object') {
          opt = {}
        }
  
        options.key[key] = true // track manually set keys.
  
        if (opt.alias) self.alias(key, opt.alias)
  
        const demand = opt.demand || opt.required || opt.require
  
        // A required option can be specified via "demand: true".
        if (demand) {
          self.demand(key, demand)
        }
  
        if (opt.demandOption) {
          self.demandOption(key, typeof opt.demandOption === 'string' ? opt.demandOption : undefined)
        }
  
        if ('conflicts' in opt) {
          self.conflicts(key, opt.conflicts)
        }
  
        if ('default' in opt) {
          self.default(key, opt.default)
        }
  
        if ('implies' in opt) {
          self.implies(key, opt.implies)
        }
  
        if ('nargs' in opt) {
          self.nargs(key, opt.nargs)
        }
  
        if (opt.config) {
          self.config(key, opt.configParser)
        }
  
        if (opt.normalize) {
          self.normalize(key)
        }
  
        if ('choices' in opt) {
          self.choices(key, opt.choices)
        }
  
        if ('coerce' in opt) {
          self.coerce(key, opt.coerce)
        }
  
        if ('group' in opt) {
          self.group(key, opt.group)
        }
  
        if (opt.boolean || opt.type === 'boolean') {
          self.boolean(key)
          if (opt.alias) self.boolean(opt.alias)
        }
  
        if (opt.array || opt.type === 'array') {
          self.array(key)
          if (opt.alias) self.array(opt.alias)
        }
  
        if (opt.number || opt.type === 'number') {
          self.number(key)
          if (opt.alias) self.number(opt.alias)
        }
  
        if (opt.string || opt.type === 'string') {
          self.string(key)
          if (opt.alias) self.string(opt.alias)
        }
  
        if (opt.count || opt.type === 'count') {
          self.count(key)
        }
  
        if (typeof opt.global === 'boolean') {
          self.global(key, opt.global)
        }
  
        if (opt.defaultDescription) {
          options.defaultDescription[key] = opt.defaultDescription
        }
  
        if (opt.skipValidation) {
          self.skipValidation(key)
        }
  
        const desc = opt.describe || opt.description || opt.desc
        self.describe(key, desc)
        if (opt.hidden) {
          self.hide(key)
        }
  
        if (opt.requiresArg) {
          self.requiresArg(key)
        }
      }
  
      return self
    }
    self.getOptions = () => options
  
    self.positional = function (key, opts) {
      argsert('<string> <object>', [key, opts], arguments.length)
      if (context.resets === 0) {
        throw new YError(".positional() can only be called in a command's builder function")
      }
  
      // .positional() only supports a subset of the configuration
      // options available to .option().
      const supportedOpts = ['default', 'defaultDescription', 'implies', 'normalize',
        'choices', 'conflicts', 'coerce', 'type', 'describe',
        'desc', 'description', 'alias']
      opts = objFilter(opts, (k, v) => {
        let accept = supportedOpts.indexOf(k) !== -1
        // type can be one of string|number|boolean.
        if (k === 'type' && ['string', 'number', 'boolean'].indexOf(v) === -1) accept = false
        return accept
      })
  
      // copy over any settings that can be inferred from the command string.
      const fullCommand = context.fullCommands[context.fullCommands.length - 1]
      const parseOptions = fullCommand ? command.cmdToParseOptions(fullCommand) : {
        array: [],
        alias: {},
        default: {},
        demand: {}
      }
      Object.keys(parseOptions).forEach((pk) => {
        if (Array.isArray(parseOptions[pk])) {
          if (parseOptions[pk].indexOf(key) !== -1) opts[pk] = true
        } else {
          if (parseOptions[pk][key] && !(pk in opts)) opts[pk] = parseOptions[pk][key]
        }
      })
      self.group(key, usage.getPositionalGroupName())
      return self.option(key, opts)
    }
  
    self.group = function group (opts, groupName) {
      argsert('<string|array> <string>', [opts, groupName], arguments.length)
      const existing = preservedGroups[groupName] || groups[groupName]
      if (preservedGroups[groupName]) {
        // we now only need to track this group name in groups.
        delete preservedGroups[groupName]
      }
  
      const seen = {}
      groups[groupName] = (existing || []).concat(opts).filter((key) => {
        if (seen[key]) return false
        return (seen[key] = true)
      })
      return self
    }
    // combine explicit and preserved groups. explicit groups should be first
    self.getGroups = () => Object.assign({}, groups, preservedGroups)
  
    // as long as options.envPrefix is not undefined,
    // parser will apply env vars matching prefix to argv
    self.env = function (prefix) {
      argsert('[string|boolean]', [prefix], arguments.length)
      if (prefix === false) options.envPrefix = undefined
      else options.envPrefix = prefix || ''
      return self
    }
  
    self.wrap = function (cols) {
      argsert('<number|null|undefined>', [cols], arguments.length)
      usage.wrap(cols)
      return self
    }
  
    let strict = false
    self.strict = function (enabled) {
      argsert('[boolean]', [enabled], arguments.length)
      strict = enabled !== false
      return self
    }
    self.getStrict = () => strict
  
    let parserConfig = {}
    self.parserConfiguration = function parserConfiguration (config) {
      argsert('<object>', [config], arguments.length)
      parserConfig = config
      return self
    }
    self.getParserConfiguration = () => parserConfig
  
    self.showHelp = function (level) {
      argsert('[string|function]', [level], arguments.length)
      if (!self.parsed) self._parseArgs(processArgs) // run parser, if it has not already been executed.
      if (command.hasDefaultCommand()) {
        context.resets++ // override the restriction on top-level positoinals.
        command.runDefaultBuilderOn(self, true)
      }
      usage.showHelp(level)
      return self
    }
  
    let versionOpt = null
    self.version = function version (opt, msg, ver) {
      const defaultVersionOpt = 'version'
      argsert('[boolean|string] [string] [string]', [opt, msg, ver], arguments.length)
  
      // nuke the key previously configured
      // to return version #.
      if (versionOpt) {
        deleteFromParserHintObject(versionOpt)
        usage.version(undefined)
        versionOpt = null
      }
  
      if (arguments.length === 0) {
        ver = guessVersion()
        opt = defaultVersionOpt
      } else if (arguments.length === 1) {
        if (opt === false) { // disable default 'version' key.
          return self
        }
        ver = opt
        opt = defaultVersionOpt
      } else if (arguments.length === 2) {
        ver = msg
        msg = null
      }
  
      versionOpt = typeof opt === 'string' ? opt : defaultVersionOpt
      msg = msg || usage.deferY18nLookup('Show version number')
  
      usage.version(ver || undefined)
      self.boolean(versionOpt)
      self.describe(versionOpt, msg)
      return self
    }
  
    function guessVersion () {
      const obj = pkgUp()
  
      return obj.version || 'unknown'
    }
  
    let helpOpt = null
    self.addHelpOpt = self.help = function addHelpOpt (opt, msg) {
      const defaultHelpOpt = 'help'
      argsert('[string|boolean] [string]', [opt, msg], arguments.length)
  
      // nuke the key previously configured
      // to return help.
      if (helpOpt) {
        deleteFromParserHintObject(helpOpt)
        helpOpt = null
      }
  
      if (arguments.length === 1) {
        if (opt === false) return self
      }
  
      // use arguments, fallback to defaults for opt and msg
      helpOpt = typeof opt === 'string' ? opt : defaultHelpOpt
      self.boolean(helpOpt)
      self.describe(helpOpt, msg || usage.deferY18nLookup('Show help'))
      return self
    }
  
    const defaultShowHiddenOpt = 'show-hidden'
    options.showHiddenOpt = defaultShowHiddenOpt
    self.addShowHiddenOpt = self.showHidden = function addShowHiddenOpt (opt, msg) {
      argsert('[string|boolean] [string]', [opt, msg], arguments.length)
  
      if (arguments.length === 1) {
        if (opt === false) return self
      }
  
      const showHiddenOpt = typeof opt === 'string' ? opt : defaultShowHiddenOpt
      self.boolean(showHiddenOpt)
      self.describe(showHiddenOpt, msg || usage.deferY18nLookup('Show hidden options'))
      options.showHiddenOpt = showHiddenOpt
      return self
    }
  
    self.hide = function hide (key) {
      argsert('<string|object>', [key], arguments.length)
      options.hiddenOptions.push(key)
      return self
    }
  
    self.showHelpOnFail = function showHelpOnFail (enabled, message) {
      argsert('[boolean|string] [string]', [enabled, message], arguments.length)
      usage.showHelpOnFail(enabled, message)
      return self
    }
  
    var exitProcess = true
    self.exitProcess = function (enabled) {
      argsert('[boolean]', [enabled], arguments.length)
      if (typeof enabled !== 'boolean') {
        enabled = true
      }
      exitProcess = enabled
      return self
    }
    self.getExitProcess = () => exitProcess
  
    var completionCommand = null
    self.completion = function (cmd, desc, fn) {
      argsert('[string] [string|boolean|function] [function]', [cmd, desc, fn], arguments.length)
  
      // a function to execute when generating
      // completions can be provided as the second
      // or third argument to completion.
      if (typeof desc === 'function') {
        fn = desc
        desc = null
      }
  
      // register the completion command.
      completionCommand = cmd || completionCommand || 'completion'
      if (!desc && desc !== false) {
        desc = 'generate completion script'
      }
      self.command(completionCommand, desc)
  
      // a function can be provided
      if (fn) completion.registerFunction(fn)
  
      return self
    }
  
    self.showCompletionScript = function ($0, cmd) {
      argsert('[string] [string]', [$0, cmd], arguments.length)
      $0 = $0 || self.$0
      _logger.log(completion.generateCompletionScript($0, cmd || completionCommand || 'completion'))
      return self
    }
  
    self.getCompletion = function (args, done) {
      argsert('<array> <function>', [args, done], arguments.length)
      completion.getCompletion(args, done)
    }
  
    self.locale = function (locale) {
      argsert('[string]', [locale], arguments.length)
      if (arguments.length === 0) {
        guessLocale()
        return y18n.getLocale()
      }
      detectLocale = false
      y18n.setLocale(locale)
      return self
    }
  
    self.updateStrings = self.updateLocale = function (obj) {
      argsert('<object>', [obj], arguments.length)
      detectLocale = false
      y18n.updateLocale(obj)
      return self
    }
  
    let detectLocale = true
    self.detectLocale = function (detect) {
      argsert('<boolean>', [detect], arguments.length)
      detectLocale = detect
      return self
    }
    self.getDetectLocale = () => detectLocale
  
    var hasOutput = false
    var exitError = null
    // maybe exit, always capture
    // context about why we wanted to exit.
    self.exit = (code, err) => {
      hasOutput = true
      exitError = err
      if (exitProcess) process.exit(code)
    }
  
    // we use a custom logger that buffers output,
    // so that we can print to non-CLIs, e.g., chat-bots.
    const _logger = {
      log () {
        const args = []
        for (let i = 0; i < arguments.length; i++) args.push(arguments[i])
        if (!self._hasParseCallback()) console.log.apply(console, args)
        hasOutput = true
        if (output.length) output += '\n'
        output += args.join(' ')
      },
      error () {
        const args = []
        for (let i = 0; i < arguments.length; i++) args.push(arguments[i])
        if (!self._hasParseCallback()) console.error.apply(console, args)
        hasOutput = true
        if (output.length) output += '\n'
        output += args.join(' ')
      }
    }
    self._getLoggerInstance = () => _logger
    // has yargs output an error our help
    // message in the current execution context.
    self._hasOutput = () => hasOutput
  
    self._setHasOutput = () => {
      hasOutput = true
    }
  
    let recommendCommands
    self.recommendCommands = function (recommend) {
      argsert('[boolean]', [recommend], arguments.length)
      recommendCommands = typeof recommend === 'boolean' ? recommend : true
      return self
    }
  
    self.getUsageInstance = () => usage
  
    self.getValidationInstance = () => validation
  
    self.getCommandInstance = () => command
  
    self.terminalWidth = () => {
      argsert([], 0)
      return typeof process.stdout.columns !== 'undefined' ? process.stdout.columns : null
    }
  
    Object.defineProperty(self, 'argv', {
      get: () => self._parseArgs(processArgs),
      enumerable: true
    })
  
    self._parseArgs = function parseArgs (args, shortCircuit, _calledFromCommand, commandIndex) {
      let skipValidation = !!_calledFromCommand
      args = args || processArgs
  
      options.__ = y18n.__
      options.configuration = self.getParserConfiguration()
  
      const populateDoubleDash = !!options.configuration['populate--']
      const config = Object.assign({}, options.configuration, {
        'populate--': true
      })
      const parsed = Parser.detailed(args, Object.assign({}, options, {
        configuration: config
      }))
  
      let argv = parsed.argv
      if (parseContext) argv = Object.assign({}, argv, parseContext)
      const aliases = parsed.aliases
  
      argv.$0 = self.$0
      self.parsed = parsed
  
      try {
        guessLocale() // guess locale lazily, so that it can be turned off in chain.
  
        // while building up the argv object, there
        // are two passes through the parser. If completion
        // is being performed short-circuit on the first pass.
        if (shortCircuit) {
          return (populateDoubleDash || _calledFromCommand) ? argv : self._copyDoubleDash(argv)
        }
  
        // if there's a handler associated with a
        // command defer processing to it.
        if (helpOpt) {
          // consider any multi-char helpOpt alias as a valid help command
          // unless all helpOpt aliases are single-char
          // note that parsed.aliases is a normalized bidirectional map :)
          const helpCmds = [helpOpt]
            .concat(aliases[helpOpt] || [])
            .filter(k => k.length > 1)
          // check if help should trigger and strip it from _.
          if (~helpCmds.indexOf(argv._[argv._.length - 1])) {
            argv._.pop()
            argv[helpOpt] = true
          }
        }
  
        const handlerKeys = command.getCommands()
        const requestCompletions = completion.completionKey in argv
        const skipRecommendation = argv[helpOpt] || requestCompletions
        const skipDefaultCommand = skipRecommendation && (handlerKeys.length > 1 || handlerKeys[0] !== '$0')
  
        if (argv._.length) {
          if (handlerKeys.length) {
            let firstUnknownCommand
            for (let i = (commandIndex || 0), cmd; argv._[i] !== undefined; i++) {
              cmd = String(argv._[i])
              if (~handlerKeys.indexOf(cmd) && cmd !== completionCommand) {
                // commands are executed using a recursive algorithm that executes
                // the deepest command first; we keep track of the position in the
                // argv._ array that is currently being executed.
                const innerArgv = command.runCommand(cmd, self, parsed, i + 1)
                return populateDoubleDash ? innerArgv : self._copyDoubleDash(innerArgv)
              } else if (!firstUnknownCommand && cmd !== completionCommand) {
                firstUnknownCommand = cmd
                break
              }
            }
  
            // run the default command, if defined
            if (command.hasDefaultCommand() && !skipDefaultCommand) {
              const innerArgv = command.runCommand(null, self, parsed)
              return populateDoubleDash ? innerArgv : self._copyDoubleDash(innerArgv)
            }
  
            // recommend a command if recommendCommands() has
            // been enabled, and no commands were found to execute
            if (recommendCommands && firstUnknownCommand && !skipRecommendation) {
              validation.recommendCommands(firstUnknownCommand, handlerKeys)
            }
          }
  
          // generate a completion script for adding to ~/.bashrc.
          if (completionCommand && ~argv._.indexOf(completionCommand) && !requestCompletions) {
            if (exitProcess) setBlocking(true)
            self.showCompletionScript()
            self.exit(0)
          }
        } else if (command.hasDefaultCommand() && !skipDefaultCommand) {
          const innerArgv = command.runCommand(null, self, parsed)
          return populateDoubleDash ? innerArgv : self._copyDoubleDash(innerArgv)
        }
  
        // we must run completions first, a user might
        // want to complete the --help or --version option.
        if (requestCompletions) {
          if (exitProcess) setBlocking(true)
  
          // we allow for asynchronous completions,
          // e.g., loading in a list of commands from an API.
          const completionArgs = args.slice(args.indexOf(`--${completion.completionKey}`) + 1)
          completion.getCompletion(completionArgs, (completions) => {
            ;(completions || []).forEach((completion) => {
              _logger.log(completion)
            })
  
            self.exit(0)
          })
          return (populateDoubleDash || _calledFromCommand) ? argv : self._copyDoubleDash(argv)
        }
  
        // Handle 'help' and 'version' options
        // if we haven't already output help!
        if (!hasOutput) {
          Object.keys(argv).forEach((key) => {
            if (key === helpOpt && argv[key]) {
              if (exitProcess) setBlocking(true)
  
              skipValidation = true
              self.showHelp('log')
              self.exit(0)
            } else if (key === versionOpt && argv[key]) {
              if (exitProcess) setBlocking(true)
  
              skipValidation = true
              usage.showVersion()
              self.exit(0)
            }
          })
        }
  
        // Check if any of the options to skip validation were provided
        if (!skipValidation && options.skipValidation.length > 0) {
          skipValidation = Object.keys(argv).some(key => options.skipValidation.indexOf(key) >= 0 && argv[key] === true)
        }
  
        // If the help or version options where used and exitProcess is false,
        // or if explicitly skipped, we won't run validations.
        if (!skipValidation) {
          if (parsed.error) throw new YError(parsed.error.message)
  
          // if we're executed via bash completion, don't
          // bother with validation.
          if (!requestCompletions) {
            self._runValidation(argv, aliases, {}, parsed.error)
          }
        }
      } catch (err) {
        if (err instanceof YError) usage.fail(err.message, err)
        else throw err
      }
  
      return (populateDoubleDash || _calledFromCommand) ? argv : self._copyDoubleDash(argv)
    }
  
    // to simplify the parsing of positionals in commands,
    // we temporarily populate '--' rather than _, with arguments
    // after the '--' directive. After the parse, we copy these back.
    self._copyDoubleDash = function (argv) {
      if (!argv._ || !argv['--']) return argv
      argv._.push.apply(argv._, argv['--'])
  
      // TODO(bcoe): refactor command parsing such that this delete is not
      // necessary: https://github.com/yargs/yargs/issues/1482
      try {
        delete argv['--']
      } catch (_err) {}
  
      return argv
    }
  
    self._runValidation = function runValidation (argv, aliases, positionalMap, parseErrors) {
      if (parseErrors) throw new YError(parseErrors.message)
      validation.nonOptionCount(argv)
      validation.requiredArguments(argv)
      if (strict) validation.unknownArguments(argv, aliases, positionalMap)
      validation.customChecks(argv, aliases)
      validation.limitedChoices(argv)
      validation.implications(argv)
      validation.conflicting(argv)
    }
  
    function guessLocale () {
      if (!detectLocale) return
      const locale = process.env.LC_ALL || process.env.LC_MESSAGES || process.env.LANG || process.env.LANGUAGE || 'en_US'
      self.locale(locale.replace(/[.:].*/, ''))
    }
  
    // an app should almost always have --version and --help,
    // if you *really* want to disable this use .help(false)/.version(false).
    self.help()
    self.version()
  
    return self
  }
  
  // allow consumers to directly use the version of yargs-parser used by yargs
  exports.Parser = Parser
  
  // rebase an absolute path to a relative one with respect to a base directory
  // exported for tests
  exports.rebase = rebase
  function rebase (base, dir) {
    return path.relative(base, dir)
  }
  