line at the end of the string) This is now optional
            (callers can pass None). It is left in its location for backwards
            compatibility. It should ''.join(lines) must == line_bytes
        :param line_bytes: A single string containing the content

        We pass both lines and line_bytes because different routes bring the
        values to this function. And for memory efficiency, we don't want to
        have to split/join on-demand.
        Nr