code: def unregister(registerable: Any):
      
      listenable = registration_event_listenable_map[type(registerable)]
      event = RegistrationEvent(registerable, RegistrationEvent.Type.UNREGISTERED)
      listenable.notify_listeners(event)
docs: Unregisters an object, notifying any listeners that may be interested in it.
      :param registerable: the object to unregister