protected Account(Customer customer,
     decimal balance, decimal interestRatePerMonth)
 {
     Customer = customer;
     Balance = balance;
     InterestRatePerMonth = interestRatePerMonth;
 }
 public DepositAccount(Customer customer,
     decimal balance, decimal interestRatePerMonth)
     : base(customer, balance, interestRatePerMonth)
 {
 }
 public MortgageAccount(Customer customer,
     decimal balance, decimal interestRatePerMonth)
     : base(customer, balance, interestRatePerMonth)
 {
 }