code: function(keys, timeout) {
    this.isDone = false;
    this.keys = keys;
    this.expected = keys.length;
    this.count = 0;
    this.timeout = timeout;
    this.data = {};
    this.errs = [];
    this.events = {
      error: null,
      timeout: null,
      done: null,
    };
    const collector = this;
    if (this.timeout) {
      this.timer = setTimeout(() => {
        const err = new Error(COLLECT_TIMEOUT);
        collector.emit('timeout', err, collector.data);
      }, timeout);
    }
  }
docs: Key Collector keys - <string[]> timeout - <number>, collect timeout, optional  Returns: <DataCollector>  Example: new KeyCollector(['config', 'users', 'cities'])