import grab
g = grab.Grab()
g.setup(timeout=2)
g.load_proxylist("proxy.txt", "text_file", "http")
g.go("http://www.yandex.ru")
print r.code

def grab_proxy(g):
    result = (False, g)
    try:
        g.go("http://www.yandex.ru")
        result = (True, g)
    except Exception as error:
        print error
        g.change_proxy()
    finally:
        return result
g = grab.Grab()
g.load_proxylist("proxy.txt", "text_file", "http")
tmp = (False, g)
while tmp[0] is False:
    tmp = grab_proxy(g)
g = tmp[1]
r = g.go("http://www.yandex.ru")
print r.code

    def check_proxy():
        with open("proxy.txt", "r") as f:
            proxy_list = [p.strip() for p in f.readlines()]
        g = Grab()
        for proxy in proxy_list:
            g.setup(proxy=proxy, proxy_type="http", connect_timeout=5, timeout=5)
            try:
                g.go("http://www.microsoft.com")
            except GrabError:
                logging.error("proxy {0} is dead. Trying next...".format(proxy))
            else:
                yield proxy

g = Grab()
g.setup(proxy=check_proxy().next())