@flow.StateHandler(next_state="Response2")
  def Response1(self, messages):
    self.state.Register("messages", messages)
    self.CallClient("ReturnBlob",
                    rdf_client.EchoRequest(data="test"),
                    next_state="Response2")
Test supported media commands with only children.
dataset/ETHPy150Open google/grr/grr/lib/flow_test.py/FlowResponseSerialization.Response1--crossover with--dataset/ETHPy150Open home-assistant/home-assistant/tests/components/media_player/test_universal.py/TestMediaPlayer.test_supported_media_commands_children_only