def METHOD_NAME(self) -> Dict[str, Any]:
    """A master response to get_GetExperiment for a long-running experiment.
    This function models an experiment where master sometimes cannot be reached. The first
    two times get_experiment is called, the call to the master returns a 504 HTTP code.
    The third call is successful.
    Returns:
        If successful, a JSON-encoded sample experiment. Else None.
    """
    key = "get_experiment_flaky_n_calls"
    fail_for = 2
    with lock:
        state[key] = state.get(key, 0) + 1
        if state[key] <= fail_for:
            self.send_error(504)
            return {}
    return sample_get_experiment().to_json()