private MenuOptionResult FeedMoney()
{
decimal initialBalance = vendingMachine.Balance;
int inputAmount = GetInteger("Enter amount in U.S. dollars", 0, new int [] { 1, 2, 5, 10 });
decimal newBalance = vendingMachine.FeedMoney(inputAmount);
Console.WriteLine($"Your new balance is {newBalance:c}.");
vendingMachine.AuditLog("FEED MONEY:", initialBalance, newBalance);
return(MenuOptionResult.WaitAfterMenuSelection);
}
