src/transformers/tokenization_utils_base.py/PreTrainedTokenizerBase/convert_tokens_to_string
class PreTrainedTokenizerBase:    def convert_tokens_to_string(self, tokens: List[str]) -> str:
        """
        Converts a sequence of tokens in a single string. The most simple way to do it is ``" ".join(tokens)`` but we
        often want to remove sub-word tokenization artifacts at the same time.

        Args:
            tokens (:obj:`List[str]`): The token to join in a string.

        Returns:
            :obj:`str`: The joined tokens.
        """
        raise NotImplementedError