def METHOD_NAME(self, src_tokens, src_lengths, constraints=None):
    if constraints is not None:
        # Though see Susanto et al. (ACL 2020): https://www.aclweb.org/anthology/2020.acl-main.325/
        raise NotImplementedError(
            "Constrained decoding with the translation_lev task is not supported"
        )
    return LanguagePairDataset(
        src_tokens, src_lengths, self.source_dictionary, append_bos=True
    )