docs: function AsyncSimpleIterator (options) {
    if (!(this instanceof AsyncSimpleIterator)) {
      return new AsyncSimpleIterator(options)
    }
    this.defaultOptions(options)
    AppBase.call(this)
    this.on = utils.emitter.compose.call(this, 'on', this.options)
    this.off = utils.emitter.compose.call(this, 'off', this.options)
    this.once = utils.emitter.compose.call(this, 'once', this.options)
    this.emit = utils.emitter.compose.call(this, 'emit', this.options)
  }