code: def emit(self, event, *event_args):
          
          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)
docs: 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`