Adding more than on Item to cart at time?

PHP
1

I have am working on a shopping cart, for coupong buying.
Here it only allows me to add one Item or One deal ata time into shopping cart.
How can I change this code to accept more than one deal at a time before checking out.


		{
			// add to cart
			/*
			 $cart = unserialize(JFactory::getSession()->get('cart'));
			 if (empty($cart))
				$cart = new Cart();
				*/
			// We only allow 1 item per cart from now one...
			$cart = new Cart();
			$cart->addItem($deal);
			JFactory::getSession()->set('cart', serialize($cart));

			$dealName = $deal->name;
			$buy4friend = $_GET['buy4friend'];
			$cartItemCount = $cart->getItem($dealId)->getCount();

			if($buy4friend == 1) {
				$msg = $dealName . " :::<b> ". JText::_("DEAL_ADD_TO_CART_MESUN");
				$link = JRoute::_("index.php?option=com_enmasse&controller=shopping&task=viewCart&buy4friend=1", false);
				JFactory::getApplication()->redirect($link, $msg);
			}else{
				$msg = $dealName . " ". JText::_( "DEAL_ADD_TO_CART");
				$link = JRoute::_("index.php?option=com_enmasse&controller=shopping&task=viewCart&buy4friend=0", false);
				JFactory::getApplication()->redirect($link, $msg);
			}
2 

// We only allow 1 item per cart from now one...
[B][COLOR="Red"]$cart = new Cart();[/COLOR][/B]
$cart->addItem($deal);

Try commenting out the line in red