class Queue:
"""
Implementation of Queue data structure using
singly-linked list.
"""
def __init__(self):
self.queue = LinkedList()
def __len__(self):
return len(self.queue)
def __str__(self):
return str(self.queue)
def enqueue(self, x):
"""
Add element x to the queue.
"""
self.queue.push(x)
def dequeue(self):
"""
Remove first element of the queue.
"""
self.queue.delete_index(0)
