def METHOD_NAME(self, tokens):
    """Converts a sequence of tokens (string) in a single string."""
    current_sub_tokens = []
    out_string = ""
    for token in tokens:
        # make sure that special tokens are not decoded using sentencepiece model
        if token in self.all_special_tokens:
            out_string += self.sp_model.decode(current_sub_tokens) + token
            current_sub_tokens = []
        else:
            current_sub_tokens.append(token)
    out_string += self.sp_model.decode(current_sub_tokens)
    return out_string.strip()