old_contents: from __future__ import print_function
  
  
  class Queue(object):
  	def __init__(self):
  		self.items = []
  
  	def is_empty(self):
  		return self.items == []
  
  	def enqueue(self, item):
  		self.items.insert(0, item)
  
  	def dequeue(self):
  		return self.items.pop()
  	
  	def size(self):
  		return len(self.items)
  
new_contents: from __future__ import print_function
  
  
  class Queue(object):
  	"""Queue class."""
  	def __init__(self):
  		self.items = []
  
  	def is_empty(self):
  		return self.items == []
  
  	def enqueue(self, item):
  		self.items.insert(0, item)
  
  	def dequeue(self):
  		return self.items.pop()
  	
  	def size(self):
  		return len(self.items)
  
subject: Add doc string.