Wrox.ProCSharp.JupiterBank.GoldAccount.PayIn C# (CSharp) Method

        public void PayIn(decimal amount) => _balance += amount;

        static void Main()
        {
            IBankAccount venusAccount = new SaverAccount();
            IBankAccount jupiterAccount = new GoldAccount();

            venusAccount.PayIn(200);
            venusAccount.Withdraw(100);
            WriteLine(venusAccount.ToString());

            jupiterAccount.PayIn(500);
            jupiterAccount.Withdraw(600);
            jupiterAccount.Withdraw(100);
            WriteLine(jupiterAccount.ToString());
        }