code: def test_topological_nested_groups():
      execution_date = pendulum.parse("20200101")
      with DAG("test_dag_edges", start_date=execution_date) as dag:
          task1 = EmptyOperator(task_id="task1")
          task5 = EmptyOperator(task_id="task5")
          with TaskGroup("group_a") as group_a:
              with TaskGroup("group_b"):
                  task2 = EmptyOperator(task_id="task2")
                  task3 = EmptyOperator(task_id="task3")
                  task4 = EmptyOperator(task_id="task4")
                  task2 >> [task3, task4]
  
          task1 >> group_a
          group_a >> task5
  
      def nested_topo(group):
          return [
              nested_topo(node) if isinstance(node, TaskGroup) else node
              for node in group.topological_sort()
          ]
  
      topological_list = nested_topo(dag.task_group)
  
      assert topological_list == [
          task1,
          [
              [
                  task2,
                  task3,
                  task4,
              ],
          ],
          task5,
      ]
  
imports: from __future__ import annotations
  from datetime import timedelta
  import pendulum
  import pytest
  from airflow.decorators import dag, setup, task, task_group, teardown
  from airflow.exceptions import TaskAlreadyInTaskGroup
  from airflow.models.baseoperator import BaseOperator
  from airflow.models.dag import DAG
  from airflow.models.xcom_arg import XComArg
  from airflow.operators.bash import BashOperator
  from airflow.operators.empty import EmptyOperator
  from airflow.operators.python import PythonOperator
  from airflow.utils.dag_edges import dag_edges
  from airflow.utils.task_group import TaskGroup, task_group_to_dict
  from tests.models import DEFAULT_DATE
label_desc: Use image node_id 25 for calling a global function with example usage: test_topological_nested_groups() and returns: unknown