public static function get(string $param, string $appname = null)
    {
        if (isset(self::$framework_paths[$param])) {
            if (!is_array(self::$framework_paths[$param]) &&
                strpos(self::$framework_paths[$param], "%app_name%") !== false) {
                if ($appname != null) {
                    return (str_replace(
                        "%app_name%",
                        $appname,
                        self::$framework_paths[$param]
                    ));
                } elseif (isset(self::$framework_paths["app.call"])) {
                    return (str_replace(
                        "%app_name%",
                        self::$framework_paths["app.call"],
                        self::$framework_paths[$param]
                    ));
                } else {
                    throw new Server500(new ArrayObject(array("explain" =>
                        "Undefined [app.call] index", "solution" =>
                        "Please refer to the framework documentation to get the proper path.")));
                }
            } else {
                return (self::$framework_paths[$param]);
            }
        } else {
            throw new Server500(new ArrayObject(array("explain" =>
                "Undefined [$param] path", "solution" =>
                "Please refer to the framework documentation to get the proper path.")));
        }
    }