def range_for_length(self, length):
        if len(self.ranges) != 1:
            return None
        begin, end = self.ranges[0]
        if length is None:
            # Unknown; only works with ranges with no end-point
            if end is None:
                return (begin, end)
            return None
        if end >= length:
            # Overshoots the end
            return None
        return (begin, end)
Return a list of available standard images (this call might take up
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/webob_0_9/webob/byterange.py/Range.range_for_length--crossover with--dataset/ETHPy150Open apache/libcloud/libcloud/compute/drivers/cloudsigma.py/CloudSigma_1_0_NodeDriver.list_images