public function toXMLString()
 {
     $str = '';
     $str .= '<ns:DoExpressCheckoutPaymentReq>';
     if ($this->DoExpressCheckoutPaymentRequest != NULL) {
         $str .= '<ns:DoExpressCheckoutPaymentRequest>';
         $str .= $this->DoExpressCheckoutPaymentRequest->toXMLString();
         $str .= '</ns:DoExpressCheckoutPaymentRequest>';
     }
     $str .= '</ns:DoExpressCheckoutPaymentReq>';
     return $str;
 }
 public function toXMLString()
 {
     $str = '';
     $str .= parent::toXMLString();
     return $str;
 }
 function DoUATPExpressCheckoutPaymentRequestType()
 {
     parent::DoExpressCheckoutPaymentRequestType();
     $this->_namespace = 'urn:ebay:api:PayPalAPI';
 }