public void NotEnoughCoinsState(IProduct product)
        {
            DisplayMessage.Push(Tags.Price);
            DisplayAmount.Push($"{product.Cost:C}");

            StartState();
        }
        public void MadePurchaseState(IProduct product)
        {
            ProductReturn.Deposit(product);
            DisplayMessage.Push("THANK YOU");
            MakeChange(product.Cost);

            StartState();
        }
 public void StartState()
 {
     DisplayMessage.Push(
         CoinInventory.TotalValue() < new decimal(0.50)
             ? Tags.ExactChange
             : Tags.InsertCoin);
     DisplayAmount.Push($"{TotalDeposit:C}");
 }