def _format_samples(
        self, samples: np.ndarray, labels: Optional[np.ndarray] = None
    ) -> tuple[Any, Any]:
        """
        Subclasses can override this method to format the samples and labels before fit and predict.
        """
        return samples, labels

        Subclasses can override this method to format the samples and labels before fit and predict.
        
darts/models/forecasting/sklearn_model.py