/**
  * Calculate the total quantity requested of a given item. All items in the
  * quote with the same SKU as the given item will be counted toward the
  * total quantity.
  *
  * @param Mage_Sales_Model_Quote_Item_Abstract
  * @return int
  */
 protected function _calculateTotalQuantityRequested(Mage_Sales_Model_Quote_Item_Abstract $item)
 {
     $inventoryItems = $this->_inventoryItemSelection->selectFrom($item->getQuote()->getAllItems());
     return $this->_quantityHelper->calculateTotalQuantityRequested($item, $inventoryItems);
 }