# Implementation of the Queue ADT using a linked list.
class Queue :

  def __init__( self ):
      '''Create an empty queue.
         The queue need three attributes
         _qhead
         _qtail
         _count
      '''
      pass

  def __str__( self ):
      '''Build and return a string representaiton of the queue'''
      pass

  def is_empty( self ):
      '''Return True if the queue is empty'''
      pass

  def __len__( self ):
      '''Return the number of items in the queue.'''
      pass
    
  def enqueue( self, item ):
      '''Create a queue node with item as its data,
         then add the given item to the queue. '''
      pass

  def dequeue( self ):
      '''Remove and return the first item in the queue. '''
      pass

  # 
  def peek( self ):
      '''Return the data of the first node without removing it '''
      pass

# Private storage class for creating the linked list nodes.
class _QueueNode( object ): 
  def __init__( self, item ):
    self.item = item
    self.next = None