Implementing C#/.NET events in Python

One of the things I liked in C# is its event-system. Although you need quite a lot of code to define an event. When I saw Python supports operator overload, I thought I'd try to implement such an event system in Python, and I did in 12 lines of code:

class Event:    def __init__(self):
        self.listeners = []
    def __call__(self, *params):
        for l in self.listeners:
    def __add__(self, listener):
        return self
    def __sub__(self, listener):
        return self

This is how you can use it:

class MyClass:
   def __init__(self):
      self.Clicked = Event()
   def click(self, button):
      self.Clicked(self, button)

def onClick(sender, button):
   print 'Button clicked: %s' % button

o = MyClass()
o.Clicked += onClick # subscribe to event'Right') # Trigger the event from outside

Cool huh? :)