/**
  * @see EPSInterface::getStateById()
  */
 public function validatePostCode($sessionId, $countryId, $postCode)
 {
     try {
         $validatePostCodeStdObject = new stdClass();
         $validatePostCodeStdObject->sessionId = $sessionId;
         $validatePostCodeStdObject->countryId = $countryId;
         $validatePostCodeStdObject->postCode = $postCode;
         $response = parent::validatePostCode($validatePostCodeStdObject);
         if (isset($response->return)) {
             $resultFlag = $response->return;
         } else {
             $resultFlag = null;
         }
         return $resultFlag;
     } catch (SoapFault $sf) {
         throw new ServerException($sf);
     }
 }