public PizzaCustomizer(Pizza pizza)
        {
            _pizza = pizza;

            _availableToppings = _pizza.AvailableToppings
                                    .AsBindable()
                                    .Select(topping => new SelectableTopping(topping));

            _selectedToppings = _availableToppings
                                    .Where(selectableTopping => selectableTopping.IsSelected)
                                    .Select(selectableTopping => selectableTopping.Topping);

            _healthWarningMessage = _selectedToppings.Count()
                                    .Switch()
                                        .Case(0,
                                            "Surely you would like more toppings?")
                                        .Case(toppings => toppings >= 3,
                                            "Too many toppings!")
                                        .Default(
                                            "Perfecto!")
                                    .EndSwitch();

            _totalPrice = _selectedToppings.Sum(topping => topping.Price).Project(toppingsTotal => toppingsTotal + pizza.BasePrice);
        }
 public Pizza Save(Pizza pizza)
 {
     unitOfWork.Session.Save(pizza);
     return pizza;
 }