code: def test_start_execution(self):
      hook = StepFunctionHook(
          aws_conn_id="aws_default", region_name="us-east-1"
      )
      state_machine = hook.get_conn().create_state_machine(
          name="pseudo-state-machine",
          definition="{}",
          roleArn="arn:aws:iam::000000000000:role/Role",
      )
  
      state_machine_arn = state_machine.get("stateMachineArn")
  
      execution_arn = hook.start_execution(
          state_machine_arn=state_machine_arn,
          name=None,
          state_machine_input={},
      )
  
      assert execution_arn is not None
  
imports: from __future__ import annotations
  from moto import mock_stepfunctions
  from airflow.providers.amazon.aws.hooks.step_function import StepFunctionHook
label_desc: Use image node_id 2 for calling the TestStepFunctionHook obj's underlying member method code with example usage: obj.test_start_execution() without return types