text: class Queue {
    constructor() {
      this.linkedList = new LinkedList();
    }
  
    isEmpty () {
      return !this.linkedList.tail;
    }
  
    peek () {
      if (!this.linkedList.head) {
        return null;
      }
  
      return this.linkedList.head.value;
    }
  
    enqueue (value) {
      this.linkedList.append(value);
    }
  
    dequeue () {
      const removeHead = this.linkedList.deleteHead();
      return removeHead ? removeHead.value : null;
    }
  
    toString (callback) {
      return this.linkedList.toString(callback);
    }
  
  }