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
It is also possible to mix between classic operator/sensor and XComArg tasks:
    .. code-block:: python
        cross_downstream(from_tasks=[t1, x2(), t3], to_tasks=[x1(), t2, x3()])
    is equivalent to::
        t1 ---> x1
           \ /
        x2 -X -> t2
           / \
        t3 ---> x3
    .. code-block:: python
        x1 = x1()
        x2 = x2()
        x3 = x3()
        t1.set_downstream(x1)
        t1.set_downstream(t2)
        t1.set_downstream(x3)
        x2.set_downstream(x1)
        x2.set_downstream(t2)
        x2.set_downstream(x3)
        t3.set_downstream(x1)
        t3.set_downstream(t2)
        t3.set_downstream(x3)
    :param from_tasks: List of tasks or XComArgs to start from.
    :param to_tasks: List of tasks or XComArgs to set as downstream dependencies.
    """
    for task in from_tasks:
        task.set_downstream(to_tasks)
BaseOperatorClassList = List[Type[BaseOperator]]
@attr.s(auto_attribs=True)
class BaseOperatorLink(metaclass=ABCMeta):