text: const { NotImplementedError } = require('../extensions/index.js');
  
  const { ListNode } = require('../extensions/list-node.js');
  
  /**
   * Implement the Queue with a given interface via linked list (use ListNode extension above).
   *
   * @example
   * const queue = new Queue();
   *
   * queue.enqueue(1); // adds the element to the queue
   * queue.enqueue(3); // adds the element to the queue
   * queue.dequeue(); // returns the top element from queue and deletes it, returns 1
   * queue.getUnderlyingList() // returns { value: 3, next: null }
   */
   module.exports = class Queue {
    constructor() {
      this.head = null;
    }
  
    getUnderlyingList() {
      return this.head;
    }
  
    enqueue(value) {
      if (!this.head) {
        this.head = new ListNode(value);
      } else {
  
        let current = this.head;
    
        while (current.next) {
          current = current.next
        }
    
        current.next = new ListNode(value);
      }
    }
  
    dequeue() {
      let removed = this.head;
      this.head = this.head.next;
      
      return removed.value;
    }
  
  }