Start
  first
    task_a1
    task_b1
    task_c1
      loop_back_to_c1_once
      join
        End
        return_to_task_c1
    task_c1
      loop_back_to_c1_once
        task_c2
          go_to_stub
            stub_1
              loop_back_to_stub_1_once
                return_to_stub_1
            stub_1
              loop_back_to_stub_1_once
                go_to_stub_3
                  stub_3
                    foo