docs: def register_new_state_machines(self, model, prop_name, info):
          """ The method register self as observer newly added StateMachineModels after those were added to the list of
          state_machines hold by observed StateMachineMangerModel. The method register as observer of observable
          StateMachineMangerModel.state_machines."""
          if info['method_name'] == '__setitem__':
              self.observe_model(info['args'][1])
              self.logger.info(NotificationOverview(info))
          elif info['method_name'] == '__delitem__':
              pass
          else:
              self.logger.warning(NotificationOverview(info))