def range_for_length(self, length):
        """
            *If* there is only one range, and *if* it is satisfiable by
            the given length, then return a (start, end) non-inclusive range
            of bytes to serve.  Otherwise return None
        """
        if length is None:
            return None
        start, end = self.start, self.end
        if end is None:
            end = length
            if 0 < start:
                start += length
        if _is_content_range_valid(start, end, length):
            stop = min(end, length)
            return (start, stop)
        else:
            return None
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/webob-1.2.3/webob/byterange.py/Range.range_for_length/swapped operands of `<`