class Queue {
  constructor() {
    this._start = 0;
    this._end = 0;
    this._storage = {};
  }

  enqueue(value) {
    this._storage[this._end] = value;
    this._end ++;
  }

  dequeue() {
    if (this._size()) {
      var dequeued = this._storage[this._start];
      delete this._storage[this._start];
      this._start ++;
      return dequeued;
    }
    return 'The Queue is empty';
  }

  _size() {
    return this._end - this._start;
  }
}