如何刮取自动完成值

Question

我无法抓取自动填充值。

import urllib
from bs4 import BeautifulSoup
import urlparse

url="https://www.facebook.com/users/login"
htmltext=urllib.urlopen(url)
soup=BeautifulSoup(htmltext)
for tag in soup.findAll('form',autocomplete=True):
    raw=tag['autocomplete']
    print raw