def _update_covariates_use(self):
        """Based on the Forecasting class and the training_sample attribute, update the
        uses_[past/future/static]_covariates attributes."""
        _, past_cov, historic_future_cov, future_cov, static_cov, _ = self.train_sample

        self._uses_past_covariates = past_cov is not None
        self._uses_future_covariates = future_cov is not None
        self._uses_static_covariates = static_cov is not None
Based on the Forecasting class and the training_sample attribute, update the
        uses_[past/future/static]_covariates attributes.
darts/models/forecasting/torch_forecasting_model.py