PayPal\PayPalAPI\DoUATPExpressCheckoutPaymentReq::toXMLString PHP Метод

    public function toXMLString()
    {
        $str = '';
        $str .= '<ns:DoUATPExpressCheckoutPaymentReq>';
        if ($this->DoUATPExpressCheckoutPaymentRequest != null) {
            $str .= '<ns:DoUATPExpressCheckoutPaymentRequest>';
            $str .= $this->DoUATPExpressCheckoutPaymentRequest->toXMLString();
            $str .= '</ns:DoUATPExpressCheckoutPaymentRequest>';
        }
        $str .= '</ns:DoUATPExpressCheckoutPaymentReq>';
        return $str;
    }