python ip代理简单问题

 import requests
import re
from bs4 import BeautifulSoup as bs

def proxy_check():
proxy={'http':'221.216.94.77:808'}
r=requests.get('http://1212.ip138.com/ic.asp',proxies=proxy)
print r.content

proxy_check()

提示错误：
requests.exceptions.MissingSchema: Proxy URLs must have explicit schemes.

proxy={'http':'http://221.216.94.77:808'} 加上URL schema