public static function create($engine, $args = null)
    {
        $engine = strtolower($engine);
        if (self::validEngine($engine)) {
            return (isset($args)) ? self::createWithArgs($engine, $args) : self::createWithArgs($engine, array());
        }
        throw new \Franzip\SerpFetcher\Exceptions\UnsupportedEngineException('Invalid SerpFetcher $engine: unknown/unsupported Search Engine. Supported engines are: \'google\', \'ask\', \'bing\', \'yahoo\'');
    }