public static function newRuntime ($group_name, $access_token, $opts = NULL) {
        if (is_null($opts)) {
            $opts = array();
        }

        // It is valid to create and use the runtime before it is fully configured.
        // The only constraint is that it will not be able to flush data until the
        // configuration is complete.
        if ($group_name != NULL) {
            $opts['group_name'] = $group_name;
        }
        if ($group_name != NULL) {
           $opts['access_token'] = $access_token;
        }
        return new TraceguideBase\Client\ClientRuntime($opts);
    }