Removes the given *callback* from the given *events* (string or list of
        strings).

def off(self, events, callback):
        """
        Removes the given *callback* from the given *events* (string or list of
        strings).
        """
        if isinstance(events, (str, unicode)):
            events = [events]
        for event in events:
            for callback_obj in self._on_off_events[event]:
                if callback_obj['callback'] == callback:
                    try:
                        del self._on_off_events[event]
                    except KeyError:
                        pass