flight\core\Loader::addDirectory PHP Method

    public static function addDirectory($dir)
    {
        if (is_array($dir) || is_object($dir)) {
            foreach ($dir as $value) {
                self::addDirectory($value);
            }
        } else {
            if (is_string($dir)) {
                if (!in_array($dir, self::$dirs)) {
                    self::$dirs[] = $dir;
                }
            }
        }
    }