public function shipmentSaveBefore(Varien_Event_Observer $observer)
 {
     /* @var $shipment Mage_Sales_Model_Order_Shipment */
     $shipment = $observer->getShipment();
     if ($shipment->getOrder()->getDcOrderId() && !$shipment->getDcOrderId()) {
         $result = Dutycalculator_Charge_Model_Importdutytaxes::shipmentCalculation($shipment);
         if ($result) {
             $shipment->setDcOrderId($result['dc_order_id']);
         }
     }
     $shipment->setDeliveryDutyType($shipment->getOrder()->getDeliveryDutyType());
     $shipment->setFailedCalculation($shipment->getOrder()->getFailedCalculation());
     return $this;
 }