PayPal\PayPalAPI\DoReferenceTransactionReq::toXMLString PHP Method

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