python ipv6 ipv4 掩码转前缀 mask to prefix

将网络掩码转前缀的代码完整版本，适应v4与v6。 在IPy工具包下，v6不支持使用mask，必须是prefix

ipv4_mask2prefix = lambda mask: sum(bin(int(i, 10)).count('1') for i in mask.split('.'))
ipv6_mask2prefix = lambda mask: sum(bin(int(i, 16)).count('1') for i in mask.split(':'))
mask2prefix = lambda mask: ipv4_mask2prefix(mask) if mask.find(".") > 0 else ipv6_mask2prefix(mask)

>>> mask2prefix("255.255.255.128")
25
>>> mask2prefix('ffff:ffff:ffff:ffff:ffff:ffff:ffff:fffe')
127