'source : Event source (publisher)
handler : A "weak handler" callback
removeData :  The identifier used for removal of the handler'

def __init__(self, source, handler, removeData):

    self.source = weakref.ref(source, self._forgetMe)
    self.obj = weakref.ref(handler.im_self, self._forgetMe)
    self.method = handler.im_func
    self.removeData = removeData
    self.name = str(handler)
