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
"""A mapped task group.
    This doesn't really do anything special, just holds some additional metadata
    for expansion later.
    Don't instantiate this class directly; call *expand* or *expand_kwargs* on
    a ``@task_group`` function instead.
    """
    def __init__(self, *, expand_input: ExpandInput, **kwargs: Any) -> None: