Method dequeue

src/data-structures/queue/Queue.js:45–48

* Remove the element at the front of the queue (the head of the linked list). * If the queue is empty, return null. * @return {*}

()

   * @return {*}
   */
  dequeue() {
    const removedHead = this.linkedList.deleteHead();
    return removedHead ? removedHead.value : null;
  }

  /**
   * @param [callback]