def METHOD_NAME(self, scenario_config_id: str, scenario_config: ScenarioConfig):
    if scenario_config.frequency and not isinstance(scenario_config.frequency, Frequency):
        self._error(
            scenario_config._FREQUENCY_KEY,
            scenario_config.frequency,
            f"{scenario_config._FREQUENCY_KEY} field of ScenarioConfig `{scenario_config_id}` must be"
            f" populated with a Frequency value.",
        )