Ensure that this works:

```python
@setup
def mytask():
    print("I am a setup task")

with dag_maker() as dag:
    mytask.override(task_id='newtask')

assert len(dag.task_group.children) == 1
setup_task = dag.task_group.children["newtask"]
assert setup_task._is_setup
```
and teardown also works
"""
        Test TaskGroup serialization/deserialization.
        """
        execution_date = datetime(2020, 1, 1)
        with DAG("test_task_group_serialization", start_date=execution_date) as dag:
            task1 = EmptyOperator(task_id="task1")
            with TaskGroup("group234") as group234:
                _ = EmptyOperator(task_id="task2")
                with TaskGroup("group34") as group34:
                    _ = EmptyOperator(task_id="task3")
                    _ = EmptyOperator(task_id="task4")
            task5 = EmptyOperator(task_id="task5")
            task1 >> group234
            group34 >> task5
        dag_dict = SerializedDAG.to_dict(dag)
        SerializedDAG.validate_schema(dag_dict)
        json_dag = SerializedDAG.from_json(SerializedDAG.to_json(dag))
        self.validate_deserialized_dag(json_dag, dag)
        serialized_dag = SerializedDAG.deserialize_dag(SerializedDAG.serialize_dag(dag))
        assert serialized_dag.task_group.children
        assert serialized_dag.task_group.children.keys() == dag.task_group.children.keys()
        def check_task_group(node):