ShipmentCollection::getBasketItemShippedQuantity

public function getBasketItemShippedQuantity(BasketItem $basketItem)
{
	$quantity = 0;

	/** @var Shipment $shipment */
	foreach ($this->collection as $shipment)
	{
		if ($shipment->isShipped())
		{
			$quantity += $shipment->getShipmentItemCollection()->getBasketItemQuantity($basketItem);
		}
	}

	return $quantity;
}