    def load_dataset(self, split, epoch=1, combine=False, **kwargs) -> FairseqDataset:
        """Load a given dataset split.

        Args:
            split (str): name of the split (e.g., train, valid, test)
        """
        if split == "train":
            data_path = self.data[(epoch - 1) % len(self.data)]
            dataset = self.load_train_dataset(data_path)
        else:
            # valid/test should always be the same.
            dataset = self.load_translation_dataset(split, self.data[0])

        self.datasets[split] = dataset
        return dataset
Load a given dataset split.

Args:
split (str): name of the split (e.g., train, valid, test)
fairseq/tasks/online_backtranslation.py