code: def test_taskgroup_dag():
      """Creates a test DAG with a few operators to test on, with some in a task group."""
  
      def f(task_id):
          return f"OP:{task_id}"
  
      with DAG(
          dag_id="test_xcom_dag", default_args=DEFAULT_ARGS
      ) as dag:
          op1 = PythonOperator(python_callable=f, task_id="test_op_1")
          op4 = PythonOperator(python_callable=f, task_id="test_op_4")
          with TaskGroup("group_1") as group:
              op2 = PythonOperator(
                  python_callable=f, task_id="test_op_2"
              )
              op3 = PythonOperator(
                  python_callable=f, task_id="test_op_3"
              )
              return dag, group, (op1, op2, op3, op4)
  
imports: from __future__ import annotations
  from datetime import datetime, timedelta
  import pytest
  from airflow.models.dag import DAG
  from airflow.models.xcom_arg import XComArg
  from airflow.operators.empty import EmptyOperator
  from airflow.operators.python import PythonOperator
  from airflow.utils.edgemodifier import Label
  from airflow.utils.task_group import TaskGroup
  from airflow.www.views import dag_edges
label_desc: Use image node_id 2 for calling a global function with example usage: test_taskgroup_dag() and returns: str, task_id, dag,  group,  op1,  op2,  op3,  op4