"""Return nodes with no parents. These are first to execute and are called roots or root nodes."""
        return [task for task in self.tasks if not task.upstream_list]
    @property
    def leaves(self) -> list[Operator]:
        """Return nodes with no children. These are last to execute and are called leaves or leaf nodes."""
        return [task for task in self.tasks if not task.downstream_list]
    def topological_sort(self, include_subdag_tasks: bool = False):
        """
        Sorts tasks in topographical order, such that a task comes after any of its
        upstream dependencies.
        Deprecated in place of ``task_group.topological_sort``
        """
        from airflow.utils.task_group import TaskGroup
        def nested_topo(group):