def _assert_stochastic(self, series: np.ndarray, name_series: str):
        """Checks if the series is stochastic (number of samples is larger than one)."""
        if not series.shape[2] > 1:
            raise_log(
                ValueError(
                    f"Scorer {str(self)} is expecting `{name_series}` to be a stochastic "
                    f"timeseries (number of samples must be higher than 1, found: {series.shape[2]}).",
                ),
                logger=logger,
            )
Checks if the series is stochastic (number of samples is larger than one).
darts/ad/scorers/scorers.py