docs: public QueueElement removeTail() {
  
  		if (head == null) {
  			return null;
  		}
  
  		QueueElement result = tail;
  		if (result.previous == null) {
  			head = null;
  			tail = null;
  		} else {
  			tail = result.previous;
  			tail.next = null;
  		}
  		result.previous = null;
  		result.next = null;
  		result.queue = null;
  
  		numElements--;
  		return result;
  
  	}