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
super().__init__(**kwargs)
        self._expand_input = expand_input
        for op, _ in expand_input.iter_references():
            self.set_upstream(op)
    def iter_mapped_dependencies(self) -> Iterator[Operator]:
        """Upstream dependencies that provide XComs used by this mapped task group."""
        from airflow.models.xcom_arg import XComArg
        for op, _ in XComArg.iter_xcom_references(self._expand_input):
            yield op
    @cache
    def get_parse_time_mapped_ti_count(self) -> int:
        """Number of instances a task in this group should be mapped to, when a DAG run is created.
        This only considers literal mapped arguments, and would return *None*
        when any non-literal values are used for mapping.
        If this group is inside mapped task groups, all the nested counts are
        multiplied and accounted.
        :meta private:
        :raise NotFullyPopulated: If any non-literal mapped arguments are encountered.
        :return: The total number of mapped instances each task should have.
        """
        return functools.reduce(
            operator.mul,
            (g._expand_input.get_parse_time_mapped_ti_count() for g in self.iter_mapped_task_groups()),
        )
    def get_mapped_ti_count(self, run_id: str, *, session: Session) -> int: