code: def _find_errors_param(self):
          
  
          # NOTE: The order of the search is very important!
          if hasattr(self.estimator, 'mse_path_'):
              return self.estimator.mse_path_.mean(1)
  
          if hasattr(self.estimator, 'cv_values_'):
              return self.estimator.cv_values_.mean(0)
  
          raise YellowbrickValueError(
              "could not find errors param on {} estimator".format(
                  self.estimator.__class__.__name__
              )
          )
docs: Searches for the parameter on the estimator that contains the array of
          errors that was used to determine the optimal alpha. If it cannot find
          the parameter then a YellowbrickValueError is raised.