def _DevAppServerAuthenticate(self):
    """Authenticates the user on the dev_appserver."""
    credentials = self.auth_function()
    value = dev_appserver_login.CreateCookieData(credentials[0], True)
    self.extra_headers["Cookie"] = (value % 'dev_appserver_login="%s"; Path=/;')
dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/tools/appengine_rpc.py/AbstractRpcServer._DevAppServerAuthenticate/swapped operands of `%`