public function useRotatingFiles($level = Logger::DEBUG, $filename = null)
    {
        $filename || $filename = $this->name.'.log';
        $path = $this->settings['directory'].'/'.$filename;
        $this->monolog->pushHandler(
            $handler = new Handler\RotatingFileHandler($path, 5, $level)
        );
        $handler->setFormatter($this->getDefaultFormatter());

        return $this;
    }