Call the registered listeners for ``event``.

        The listeners will be called with any extra arguments passed to
        :meth:`emit` first, and then the extra arguments passed to :meth:`on`

def emit(self, event, *event_args):
        """Call the registered listeners for ``event``.

        The listeners will be called with any extra arguments passed to
        :meth:`emit` first, and then the extra arguments passed to :meth:`on`
        """
        listeners = self._listeners[event][:]
        for listener in listeners:
            args = list(event_args) + list(listener.user_args)
            result = listener.callback(*args)
            if result is False:
                self.off(event, listener.callback)