docs: def relieve_state_machines(self, model, prop_name, info):
          """ The method relieves observed models before those get removed from the list of state_machines hold by
          observed StateMachineMangerModel. The method register as observer of observable
          StateMachineMangerModel.state_machines."""
          if info['method_name'] == '__setitem__':
              pass
          elif info['method_name'] == '__delitem__':
              self.relieve_model(self.state_machine_manager_model.state_machines[info['args'][0]])
              if self.state_machine_manager_model.state_machines[info['args'][0]].root_state:
                  self.relieve_model(self.state_machine_manager_model.state_machines[info['args'][0]].root_state)
                  # otherwise relieved by root_state assign notification
              # self.logger.info(NotificationOverview(info))
          else:
              self.logger.warning(NotificationOverview(info))