code: def _set_tasks_state(self, value):
          
          if value not in states.state_numbers.keys():
              raise ValueError(obj=self._uid,
                               attribute='set_tasks_state',
                               expected_value=states.state_numbers.keys(),
                               actual_value=value)
  
          for task in self._tasks:
              task.state = value
docs: Purpose: Set state of all tasks of the current stage.
  
          :arguments: String