class_docstr: Parameters
  ----------
  seasonality : int
      Length of seasonality
  seasonality_sm_input : float
      float value between [0, 1], applicable only if `seasonality` > 1. A larger value puts
      more weight on the current seasonality.
      If None, the model will estimate this value.
  level_sm_input : float
      float value between [0.0001, 1]. A larger value puts more weight on the current level.
      If None, the model will estimate this value.
class_docstr_tok: ["Parameters","--","--","--","--","--","seasonality",":","int","Length","of","seasonality","seasonality_sm_input",":","float","float","value","between","[","0",",","1","]",",","applicable","only","if","`","seasonality","`",">","1",".","A","larger","value","puts","more","weight","on","the","current","seasonality",".","If","None",",","the","model","will","estimate","this","value",".","level_sm_input",":","float","float","value","between","[","0.0001",",","1","]",".","A","larger","value","puts","more","weight","on","the","current","level",".","If","None",",","the","model","will","estimate","this","value","."]
code: def _set_valid_response(self, training_meta):
      response = training_meta[TrainingMetaKeys.RESPONSE.value]
      self.is_valid_response = (~np.isnan(response)).astype(int)
      # raise exception if the first response value is missing
      if self.is_valid_response[0] == 0:
          raise DataInputException(
              "The first value of response column {} cannot be missing..".format(
                  training_meta[TrainingMetaKeys.RESPONSE_COL.value]
              )
          )
  
imports: import numpy
  from copy import deepcopy
  import torch
  from enum import Enum
  from ..constants.constants import PredictionKeys, TrainingMetaKeys, PredictionMetaKeys
  from ..exceptions import IllegalArgument, DataInputException
  from .model_template import ModelTemplate
  from ..estimators.stan_estimator import StanEstimatorMCMC, StanEstimatorMAP
  from ..utils.features import moving_average
label_desc: Use image node_id 4 for calling the ETSModel obj's underlying member method code with example usage: obj._set_valid_response(training_meta) without return types