public function getCurrency($lang = null)
    {
        if (!is_null($lang)) {
            $original_lang = $this->getLanguage();
            $this->setLanguage($lang);
        }
        $formatter = new NumberFormatter($this->getLocale(), NumberFormatter::CURRENCY);
        $currency = $formatter->getTextAttribute(NumberFormatter::CURRENCY_CODE);
        if (!empty($original_lang)) {
            $this->setLanguage($original_lang);
        }
        return $currency;
    }