private static void TestDepositAccounts()
        {
            Customer haron            = new Individual("Haron", "Kipkorir");
            Customer bugati           = new Company("Bugatti cars");
            Customer trendyCollection = new Company("Trendy T Collections");
            Customer kuddah           = new Individual("Anthony", "Karuen");

            Account haronAccount  = new DepositAccount(haron, 1200, 1.5f);
            Account bugatiAccount = new DepositAccount(bugati, 1.6f);
            Account kuddahAccount = new DepositAccount(kuddah, -200, 2.3f);
            Account trendyAccount = new DepositAccount(trendyCollection, 5200, 2.3f);

            Console.WriteLine(haronAccount);
            double interest = haronAccount.CalculateInterest(12);

            Console.WriteLine("Haron Interest: {0}", interest);
            Console.WriteLine("Account balance after withdrawal: {0}", haronAccount.Withdraw(400d));
            Console.WriteLine("Haron's Interest after withdrawal: {0}", haronAccount.CalculateInterest(12));
            Console.WriteLine("Account balance after withdrawal: {0}", haronAccount.Withdraw(900));

            Console.WriteLine();
            Console.WriteLine(bugatiAccount);
            Console.WriteLine(kuddahAccount);
            Console.WriteLine(trendyAccount);

            kuddahAccount.Withdraw(200);
            interest = kuddahAccount.CalculateInterest(2);
        }
        private static void TestBank()
        {
            Customer ilara           = new Company("Ilara Yoghurt");
            Customer bugati          = new Company("Bugatti cars");
            Customer blackCollection = new Company("Black Collections");
            Customer haron           = new Individual("Haron", "Kipkorir");
            Customer brian           = new Individual("Brian", "Smit");
            Customer natLiv          = new Individual("Natalie", "Olivia");

            Account haronAccount  = new DepositAccount(haron, 1200, 1.5f);
            Account ilaraAccount  = new LoanAccount(ilara, 8700, 2.4f);
            Account bugatiAccount = new MortgageAccount(bugati, 1000, 2.3f);
            Account blackAccount  = new DepositAccount(blackCollection, 1230, 1.3f);
            Account brianAccount  = new LoanAccount(brian, 300, 0f);
            Account natLivAccount = new DepositAccount(natLiv, 200, 2.0f);

            Bank worldBank = new Bank("World Bank");

            worldBank.Customers.Add(ilara);
            worldBank.Customers.Add(bugati);
            worldBank.Customers.Add(blackCollection);
            worldBank.Customers.Add(haron);
            worldBank.Customers.Add(brian);
            worldBank.Customers.Add(natLiv);

            worldBank.Accounts.Add(haronAccount);
            worldBank.Accounts.Add(ilaraAccount);
            worldBank.Accounts.Add(bugatiAccount);
            worldBank.Accounts.Add(blackAccount);
            worldBank.Accounts.Add(brianAccount);
            worldBank.Accounts.Add(natLivAccount);

            Console.WriteLine(worldBank);
        }