static void Main(string[] args)
        {
            Customer customer = new Customer(name: "Joe", isVeteran: false)
            {
                DateOfBirth         = new DateTime(1980, 10, 09),
                DateOfFirstPurchase = new DateTime(2018, 11, 22)
            };

            DiscountCalculator discountCalc = new DiscountCalculator();

            Console.WriteLine("Customer's name: " + customer.Name);
            Console.WriteLine("Customer's discount rate: " + discountCalc.CalculateDiscountPercentage(customer));

            //Please check TestClass.cs for examples of what can be expected from this demo
        }