name_mangling.py

class Clown(object):
    def __init__(self, name):
        self.name = name

    def nice_hi(self):
        return "Helloooo " + self.__format_name()

    def __format_name(self):    # mangled to _Clown__format_name()
        return self.name + " (the clown)"

class ScaryClown(Clown):
    def __init__(self, name):
        Clown.__init__(self, name)

    def __format_name(self):    # mangled to _ScaryClown__format_name()
        return self.name + " (the scary clown)"

c = ScaryClown("Billy")
print c.nice_hi()    # Helloooo Billy (the clown)