def convert_tokens_to_string(tokens, clean_up_tokenization_spaces=True):
        """ Converts a sequence of tokens (string) in a single string. """

        def clean_up_tokenization(out_string):
            """ Clean up a list of simple English tokenization artifacts
            like spaces before punctuations and abreviated forms.
            """
            out_string = (
                out_string.replace(" .", ".")
                    .replace(" ?", "?")
                    .replace(" !", "!")
                    .replace(" ,", ",")
                    .replace(" ' ", "'")
                    .replace(" n't", "n't")
                    .replace(" 'm", "'m")
                    .replace(" 's", "'s")
                    .replace(" 've", "'ve")
                    .replace(" 're", "'re")
            )
            return out_string

        text = ' '.join(tokens).replace(' ##', '').strip()
        if clean_up_tokenization_spaces:
            clean_text = clean_up_tokenization(text)
            return clean_text
        else:
            return text
 Converts a sequence of tokens (string) in a single string. 
cn_clip/clip/bert_tokenizer.py