static public function group($closure)
    {
        $backtrace = debug_backtrace();
        //!isset($this) || $backtrace[0]['type'] == '::' || 
        if(self::$instance->prefix == null) {
            exit('Can not be called statically or directly. Use Route::prefix(name)->group(routes-to-be-registered)');
        }
        if($closure instanceof Closure) {
            call_user_func($closure);
        }
        self::$instance->prefix = null;
    }