src/transformers/models/t5/tokenization_t5_fast.py/T5TokenizerFast/get_sentinel_tokens
class T5TokenizerFast:    def get_sentinel_tokens(self):
        return list(
            set(filter(lambda x: bool(re.search(r"<extra_id_\d+>", x)) is not None, self.additional_special_tokens))
        )