text: class Queue {
    constructor(arr){
      this._arr = arr;
    }
    enqueue (val) {
      this._val = val;
      this._arr.push(this._val);
      return this._arr
    }
    dequeue() {
      return this._arr.shift();
    }
    front() {
      return this._arr[0];
    };
    size () {
      return this._arr.length;
    };
    isEmpty () {
      return this._arr.length === 0;
    };
  }
  
  q = new Queue([1,2,3])
  console.log(q.size())
  console.log(q.enqueue(5))
  console.log(q.size())
  