/**
* Processing additional validation to check is carrier applicable.
*
* @param Mage_Shipping_Model_Rate_Request $request
* @return Mage_Shipping_Model_Carrier_Abstract|Mage_Shipping_Model_Rate_Result_Error|boolean
*/
public function proccessAdditionalValidation(Mage_Shipping_Model_Rate_Request $request)
{
// zip code required for US
$this->_isZipCodeRequired = $this->_isUSCountry($request->getDestCountryId());
return parent::proccessAdditionalValidation($request);
}
