def remove_all_listeners(self, event=None):
        """Remove all functions for all events, or one event if one is specifed.

        :param event: Optional event you wish to remove all functions from
        """
        if event is not None:
            self._registered_events[event] = OrderedDict()
        else:
            self._registered_events = defaultdict(OrderedDict)
Remove all functions for all events, or one event if one is specifed.

        :param event: Optional event you wish to remove all functions from