public static function getInstance($config = null)
    {
        static $instance;

        $instance = $instance ? clone $instance : new self();

        if (!$config) {
            $config = new AnConfig();
        }

        $config->append(array(
            'date' => gmdate('Y-m-d H:i:s'),
        ));

        $instance->setDate($config->date);

        return $instance;
    }