code: def test_multistage_forecast_template_config():
      """Tests the `MultistageForecastTemplateConfig` data class."""
      assert (
          MultistageForecastTemplateConfig.train_length == f"{7 * 56}D"
      )
      assert MultistageForecastTemplateConfig.fit_length is None
      assert MultistageForecastTemplateConfig.agg_freq is None
      assert MultistageForecastTemplateConfig.agg_func == "nanmean"
      assert (
          MultistageForecastTemplateConfig.model_template
          == "SILVERKITE"
      )
      assert MultistageForecastTemplateConfig.model_components is None
  
file_path: greykite/greykite/tests/framework/templates/test_multistage_forecast_template_config.py
imports: from greykite.framework.templates.auto_arima_template import AutoArimaTemplate
  from greykite.framework.templates.autogen.forecast_config import ModelComponentsParam
  from greykite.framework.templates.multistage_forecast_template_config import MULTISTAGE_EMPTY
  from greykite.framework.templates.multistage_forecast_template_config import SILVERKITE_TWO_STAGE
  from greykite.framework.templates.multistage_forecast_template_config import SILVERKITE_WOW
  from greykite.framework.templates.multistage_forecast_template_config import MultistageForecastModelTemplateEnum
  from greykite.framework.templates.multistage_forecast_template_config import MultistageForecastTemplateConfig
  from greykite.framework.templates.multistage_forecast_template_config import MultistageForecastTemplateConstants
  from greykite.framework.templates.prophet_template import ProphetTemplate
  from greykite.framework.templates.silverkite_template import SilverkiteTemplate
  from greykite.framework.templates.simple_silverkite_template import SimpleSilverkiteTemplate
label_desc: Use image node_id 2 for calling a global function with example usage: test_multistage_forecast_template_config() without return types