# File app/models/kar.rb, line 4
4:   def initialize
5:     @items = []
6:   end

    # File app/models/kar.rb, line 17
17:   def totaalprijs
18:     @items.sum { |item| item.prijs }
19:   end

    # File app/models/kar.rb, line 8
 8:   def voeg_product_toe(product)
 9:    huidig_item = @items.find {|item| item.product == product}
10:    if huidig_item           # product zit reeds in de winkelkar
11:      huidig_item.verhoog_aantal
12:    else                       # dit product zit nog niet in de winkelkar
13:      @items << KarItem.new(product)
14:    end
15:   end