public function cached($cacheLife = 3600, $accessibility = 'public')
    {
        static $cached;
        // Protect sending cached headers once
        if (!isset($cached) or $cached !== true) {
            header('Expires: ' . gmdate('D, d M Y H:i:s T', time() + $cacheLife));
            header('Cache-Control: ' . $accessibility . ', max-age=' . $cacheLife);
            header('Pragma: cache');

            $cached = true;
        }
    }