src/transformers/models/transfo_xl/tokenization_transfo_xl.py/TransfoXLTokenizer/_convert_id_to_token
class TransfoXLTokenizer:    def _convert_id_to_token(self, idx):
        """Converts an id in a token (BPE) using the vocab."""
        assert 0 <= idx < len(self), f"Index {idx} out of vocabulary range"
        return self.idx2sym[idx]