xml.response(:code => @code, &proc do
  xml.items(&proc do
    @items.each(&proc do |item|
      xml.item(&proc do
        xml.sku(item.product.sku)
        xml.description(item.product.description)
        xml.unit_price(item.product.list_price, :currency => "usd")
        xml.quantity(1)
      end)
    end)
  end)
end)