Creates a :class:`~werkzeug.datastructures.ContentRange` object
        from the current range and given content length.

def make_content_range(self, length):
        """Creates a :class:`~werkzeug.datastructures.ContentRange` object
        from the current range and given content length.
        """
        rng = self.range_for_length(length)
        if rng is not None:
            return ContentRange(self.units, rng[0], rng[1], length)