Ouzo\Db::getInstance PHP Method

    public static function getInstance()
    {
        if (!self::$_instance) {
            self::$_instance = new self();
        }
        return self::$_instance;
    }

 public function __invoke()
 {
     $function = $this->_object;
     $arguments = func_get_args();
     return Db::getInstance()->runInTransaction(function () use($function, $arguments) {
         return call_user_func_array($function, $arguments);
     });
 }