def __len__(self):
        size = self.size
        if size > _sys_maxint:
            raise IndexError(
                "range contains more than %d (sys.maxint) IP addresses!"
                "Use the .size property instead." % _sys_maxint)
        return size
:return: the cardinality of this IP set (i.e. sum of individual IP             addresses). Raises ``IndexError`` if size > maxint (a Python             limitation). Use the .size property for subnets of any size.
dataset/ETHPy150Open drkjam/netaddr/netaddr/ip/sets.py/IPSet.__len__