class EventSource(object):
    def __init__(self):
        self._callbacks = []
    def register(self, callback):
        print('register:', callback)
        self._callbacks.append(callback)
    def notify(self, *args, **kwargs):
        for callback in self._callbacks:
            callback(*args, **kwargs)
class EventHandler(object):
    def __init__(self, name):
        self.name = name
    def foo(self, *args, **kwargs):
        print('foo:', self.name, *args, **kwargs)
    def bar(self, *args, **kwargs):
        print('bar:', self.name, *args, **kwargs)

print('method:', EventHandler.foo, EventHandler.bar)

s = EventSource(); x = EventHandler('x'); y = EventHandler('y')
s.register(x.foo); s.register(y.foo)
s.register(x.bar); s.register(y.bar)
s.notify('first')
s.notify('second')