with TaskGroup("a", tooltip="") as group_a:
    task1 = PythonOperator(
    task_id="stask1_id",
    python_callable=function1,
    dag=Dag
    )

    stask2 = PythonOperator(
    task_id="stask2_id",
    python_callable=function2,
    dag=Dag
    )

    task1 >> stask2