code: def test_get_regressor_cols(df, forecast_config):
      """Tests the `self.get_regressor_cols` method."""
      template = MultistageForecastTemplate()
      df["reg1"] = 1
      df["reg2"] = 2
      template.df = df
      template.config = forecast_config
      forecast_config.model_components_param.custom[
          "multistage_forecast_configs"
      ][0].model_components.regressors["regressor_cols"] = ["reg1"]
      forecast_config.model_components_param.custom[
          "multistage_forecast_configs"
      ][1].model_components.regressors["regressor_cols"] = ["reg2"]
      regressor_cols = template.get_regressor_cols()
      assert set(regressor_cols) == {"reg1", "reg2"}
  
imports: import datetime
  import numpy
  import pytest
  from testfixtures import LogCapture
  from greykite.common.constants import LOGGER_NAME
  from greykite.common.constants import PREDICTED_COL
  from greykite.common.constants import PREDICTED_LOWER_COL
  from greykite.common.constants import PREDICTED_UPPER_COL
  from greykite.common.constants import TIME_COL
  from greykite.common.constants import VALUE_COL
  from greykite.common.testing_utils import generate_df_for_tests
  from greykite.framework.templates.autogen.forecast_config import EvaluationPeriodParam
  from greykite.framework.templates.autogen.forecast_config import ForecastConfig
  from greykite.framework.templates.autogen.forecast_config import MetadataParam
  from greykite.framework.templates.autogen.forecast_config import ModelComponentsParam
  from greykite.framework.templates.forecaster import Forecaster
  from greykite.framework.templates.multistage_forecast_template import MultistageForecastTemplate
  from greykite.framework.templates.multistage_forecast_template_config import SILVERKITE_TWO_STAGE
  from greykite.framework.templates.multistage_forecast_template_config import MultistageForecastTemplateConfig
  from greykite.framework.templates.simple_silverkite_template import SimpleSilverkiteTemplate
  from greykite.sklearn.estimator.simple_silverkite_estimator import SimpleSilverkiteEstimator
  from greykite.sklearn.uncertainty.uncertainty_methods import UncertaintyMethodEnum
label_desc: Use image node_id 5 for calling a global function with example usage: test_get_regressor_cols(df, forecast_config) without return types