banking system :
-all the bank accout can be created, accessed,and clossed later.
-three type of account:current,saving,fixed deposit.
-each custormer can open more than one type of accounts.
-The transactions are deposit, withdraw, and view balance
-the account created with a deposit and creation date.
-After that money can be deposited and withdrawn.Balance will be updated accordingly
-a request for balande should display each individual account ballance as well as the total balance of all acoounts owned
customer class and an account class
customer no (3 digits)