Create dataset objects for splits of a TranslationDataset.

        Arguments:
            exts: A tuple containing the extension to path for each language.
            fields: A tuple containing the fields that will be used for data
                in each language.
            path (str): Common prefix of the splits' file paths, or None to use
                the result of cls.download(root).
            root: Root dataset storage directory. Default is '.data'.
            train: The prefix of the train data. Default: 'train'.
            validation: The prefix of the validation data. Default: 'val'.
            test: The prefix of the test data. Default: 'test'.
            Remaining keyword arguments: Passed to the splits method of
                Dataset.

def splits(cls, exts, fields, path=None, root='.data',
               train='train', validation='val', test='test', **kwargs):
        """Create dataset objects for splits of a TranslationDataset.

        Arguments:
            exts: A tuple containing the extension to path for each language.
            fields: A tuple containing the fields that will be used for data
                in each language.
            path (str): Common prefix of the splits' file paths, or None to use
                the result of cls.download(root).
            root: Root dataset storage directory. Default is '.data'.
            train: The prefix of the train data. Default: 'train'.
            validation: The prefix of the validation data. Default: 'val'.
            test: The prefix of the test data. Default: 'test'.
            Remaining keyword arguments: Passed to the splits method of
                Dataset.
        """
        if path is None:
            path = cls.download(root)

        train_data = None if train is None else cls(
            os.path.join(path, train), exts, fields, **kwargs)
        val_data = None if validation is None else cls(
            os.path.join(path, validation), exts, fields, **kwargs)
        test_data = None if test is None else cls(
            os.path.join(path, test), exts, fields, **kwargs)
        return tuple(d for d in (train_data, val_data, test_data)
                     if d is not None)