python提取根域名

#!/usr/bin/python
# -*- coding: UTF-8 -*-


import re
def getDomain(s):
    res = s
    domainS = [".com",".cn",".com.cn",".gov",".net",".edu.cn",".net.cn",".org.cn",".co.jp",".gov.cn",".co.uk","ac.cn",".edu",".tv",".info",".ac",".ag",".am",".at",".be",".biz",".bz",".cc",".de",".es",".eu",".fm",".gs",".hk",".in",".info",".io",".it",".jp",".la",".md",".ms",".name",".nl",".nu",".org",".pl",".ru",".sc",".se",".sg",".sh",".tc",".tk",".tv",".tw",".us",".co",".uk",".vc",".vg",".ws",".il",".li",".nz"]
    for l in domainS:
        regex = re.compile(r'[0-9a-zA-Z_-]+'+l+'$')
        m = regex.findall(s)
        if len(m) > 0:
            return m[0]
        else:
            pass
    return res

if"__main__":
    print getDomain("www.baidu.com")