function _checkMode($ax_args)
    {
        $mode = Auth_OpenID::arrayGet($ax_args, 'mode');
        if ($mode != $this->mode) {
            return new Auth_OpenID_AX_Error(
                            sprintf(
                                    "Expected mode '%s'; got '%s'",
                                    $this->mode, $mode));
        }

        return true;
    }