def convert_tokens_to_string(self, tokens: List[str]) -> str:
        """
        Converts a connectionist-temporal-classification (CTC) output tokens into a single string.
        """
        # group same tokens into non-repeating tokens in CTC style decoding
        grouped_tokens = [token_group[0] for token_group in groupby(tokens)]

        # filter self.pad_token which is used as CTC-blank token
        filtered_tokens = list(filter(lambda token: token != self.pad_token, grouped_tokens))

        # replace delimiter token
        string = "".join([" " if token == self.word_delimiter_token else token for token in filtered_tokens]).strip()

        if self.do_lower_case:
            string = string.lower()

        return string

        Converts a connectionist-temporal-classification (CTC) output tokens into a single string.
        
dpkd/transformers/src/transformers/models/wav2vec2/tokenization_wav2vec2.py