def to_content_range_header(self, length):
        """Converts the object into `Content-Range` HTTP header,
        based on given length
        """
        range_for_length = self.range_for_length(length)
        if range_for_length is not None:
            return "%s %d-%d/%d" % (
                self.units,
                range_for_length[0],
                range_for_length[1] - 1,
                length,
            )
        return None
Converts the object into `Content-Range` HTTP header,
        based on given length