#!/usr/bin/env python
     # encoding: utf-8
     #
     # Copyright (c) 2008 Doug Hellmann All rights reserved.
     #
     """
     """
     
     __version__ = "$Id$"
     #end_pymotw_header
     
     class BaseClass(object):
         """Defines the interface"""
         def __init__(self):
             super(BaseClass, self).__init__()
         def do_something(self):
             """The interface, not implemented"""
             raise NotImplementedError(self.__class__.__name__ + '.do_something')
     
     class SubClass(BaseClass):
         """Implementes the interface"""
         def do_something(self):
             """really does something"""
             print self.__class__.__name__ + ' doing something!'
     
     SubClass().do_something()
     BaseClass().do_something()