class_docstr: The model template for Multistage Forecast Estimator.
class_docstr_tok: ["The","model","template","for","Multistage","Forecast","Estimator","."]
docstr: Gets the regressor columns in the model.
  
  Iterates over each submodel to extract the regressor columns.
  
  Returns
  -------
  regressor_cols : `list` [`str`]
      A list of the regressor column names used in any of the submodels.
docstr_tok: ["Gets","the","regressor","columns","in","the","model",".","Iterates","over","each","submodel","to","extract","the","regressor","columns",".","Returns","--","--","--","-","regressor_cols",":","`","list","`","[","`","str","`","]","A","list","of","the","regressor","column","names","used","in","any","of","the","submodels","."]
code: def get_regressor_cols(self):
      """Gets the regressor columns in the model.
  
      Iterates over each submodel to extract the regressor columns.
  
      Returns
      -------
      regressor_cols : `list` [`str`]
          A list of the regressor column names used in any of the submodels.
      """
      templates = self.__get_regressor_templates()
      regressor_cols = []
      if templates is None or templates == []:
          return []
      for template in templates:
          try:
              regressors = template.get_regressor_cols()
          except AttributeError:
              continue
          regressor_cols += regressors if regressors is not None else []
      return unique_in_list(
          array=regressor_cols, ignored_elements=(None,)
      )
  
imports: from itertools import product
  from typing import Dict
  from typing import List
  from typing import Type
  import pandas
  from greykite.common import constants
  from greykite.common.logging import LoggingLevelEnum
  from greykite.common.logging import log_message
  from greykite.common.python_utils import unique_in_list
  from greykite.common.python_utils import update_dictionaries
  from greykite.framework.templates.autogen.forecast_config import ForecastConfig
  from greykite.framework.templates.autogen.forecast_config import MetadataParam
  from greykite.framework.templates.base_template import BaseTemplate
  from greykite.framework.templates.multistage_forecast_template_config import MultistageForecastTemplateConfig
  from greykite.framework.templates.multistage_forecast_template_config import MultistageForecastTemplateConstants
  from greykite.sklearn.estimator.base_forecast_estimator import BaseForecastEstimator
  from greykite.sklearn.estimator.multistage_forecast_estimator import MultistageForecastEstimator
  from greykite.sklearn.estimator.multistage_forecast_estimator import MultistageForecastModelConfig
label_desc: Use image node_id 4 for calling the MultistageForecastTemplate obj's underlying member method code with example usage: obj.get_regressor_cols() and returns: unique_in_list, list