src/transformers/tokenization_utils.py/PreTrainedTokenizer/_convert_token_to_id_with_added_voc
class PreTrainedTokenizer:    def _convert_token_to_id_with_added_voc(self, token):
        if token is None:
            return None

        if token in self.added_tokens_encoder:
            return self.added_tokens_encoder[token]
        return self._convert_token_to_id(token)