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.

def _find_errors_param(self):
        """
        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.
        """

        # 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__
            )
        )