Third try

async.py

def auth(login, password):
    return login == "1" and password == "test"

login_action = Write('LOGIN') >> \
               Read('login') >> \
               Write('PASS') >> \
               Read('PASS') >> \
               Guard(lambda v: auth(v['login'], v['pass']) >> \
               Write('OK')

register(login_action, socket, on_success=add_client, on_error=disconnect)