def new_message_handler(self) -> Callable[[str], None]:
        """
        :return:
            A progress handler suitable for :func:`~git.cmd.handle_process_output`,
            passing lines on to this progress handler in a suitable format.
        """

        def handler(line: AnyStr) -> None:
            return self._parse_progress_line(line.rstrip())

        # END handler

        return handler

        :return:
            A progress handler suitable for :func:`~git.cmd.handle_process_output`,
            passing lines on to this progress handler in a suitable format.
        
git/util.py