public function addAssets($cssFiles, $jsFiles, $basePath = null, $baseUrl = null)
    {
        $this->additionalAssets[] = array(
            'base_path' => $basePath,
            'base_url' => $baseUrl,
            'css' => (array) $cssFiles,
            'js' => (array) $jsFiles
        );
        return $this;
    }