def special_tokens_map(self) -> Dict[str, Union[str, List[str]]]:
        """
        `Dict[str, Union[str, List[str]]]`: A dictionary mapping special token class attributes (`cls_token`,
        `unk_token`, etc.) to their values (`'<unk>'`, `'<cls>'`, etc.).

        Convert potential tokens of `tokenizers.AddedToken` type to string.
        """
        set_attr = {}
        for attr in self.SPECIAL_TOKENS_ATTRIBUTES:
            attr_value = getattr(self, attr)
            if attr_value:
                set_attr[attr] = attr_value
        return set_attr

        `Dict[str, Union[str, List[str]]]`: A dictionary mapping special token class attributes (`cls_token`,
        `unk_token`, etc.) to their values (`'<unk>'`, `'<cls>'`, etc.).

        Convert potential tokens of `tokenizers.AddedToken` type to string.
        
dpkd/transformers/src/transformers/tokenization_utils_base.py