code: def _trigger_event(
              self, holder: T.Any, alt_name: str, action: str, *event_args: T.Any
      ) -> None:
          
  
          if isinstance(self.observable, Observable):
              observable = self.observable
          elif isinstance(self.observable, str):
              observable = getattr(holder, self.observable)
          elif isinstance(holder, Observable):
              observable = holder
          else:
              raise TypeError(
                  "This ObservableProperty is no member of an Observable "
                  "object. Specify where to find the Observable object for "
                  "triggering events with the observable keyword argument "
                  "when initializing the ObservableProperty."
              )
  
          name = alt_name if self.event is None else self.event
          event = "{}_{}".format(action, name)
          observable.trigger(event, *event_args)
docs: Triggers an event on the associated Observable object.
          The Holder is the object this property is a member of, alt_name
          is used as the event name when self.event is not set, action is
          prepended to the event name and event_args are passed through
          to the registered event handlers.