class Super:      def method(self):          print 'in Super.method'             def delegate(self):          self.action()                     class Inheritor(Super):                     pass    class Replacer(Super):                      def method(self):          print 'in Replacer.method'    class Extender(Super):                      def method(self):          print 'starting Extender.method'          Super.method(self)          print 'ending Extender.method'    class Provider(Super):                      def action(self):          print 'in Provider.action'    if __name__ == '__main__':      for klass in (Inheritor, Replacer, Extender):          print '\n' + klass.__name__ + '...'          klass().method()        print '\nProvider...'      x = Provider()      x.delegate()