text: class QueueInterface():
    """ interface for a queue adt: FIFO policy """
  
    def __init__(self):
      """ initialize a new empty queue """
      raise "QueueInterface.__init__ is not implemented"
  
    def insert(self, new_item):
      """ add a new item to the queue """
      raise "QueueInterface.insert is not implemented"""
  
    def remove(self):
      """ remove and return the item at the top of the queue """
      raise "QueueInterface.remove is not implemented"""
  
    def isEmpty(self):
      """ check whether the queue is empty """
      raise "QueueInterface.isEmpty is not implemented"""