Q22. Consider a simplified OO design, shown in Figure, for a banking system. Accounts can be created at the bank, money can be deposited and withdrawn from the account. An account is accessed by its account number. Use the Decorator design pattern to add two new banking features to the design:
(a) Overdraft protection: allows the customer to withdraw money when the account balance is zero; total amount that can be withdrawn in this feature is a predefined credit limit.
(b) Transaction fee: charges the customer a fixed fee for each deposit and withdrawal transaction.
Figure is attached. Excerpt is from Software Engineering Theory and Practice Fourth Edition, Pfleeger and Atlee

Q23. A bank must report to the government's tax institution all transactions (deposits and withdrawals) that exceed $10,000. Building on the initial design of the banking system from question 22, use the Observer design pattern to construct a class that monitors all Account transactions.