1. Interaction Diagram for each system operation
2. Design class diagram showing all relevant classes
3. Prepare walkthrough for class diagram

Notes:
Do not forget the start-up system operation that creates and initializes objects for other system operations to work with.
Also make sure to show creating and logging the information being processed by your system operations.

System Operations:
- Start Up
- Shut Down
- Print Subscriber List
- Calculate Bills
- Add Subscriber
- Modify Subscriber
- Delete Subscriber
- Add Delivery Person
- Modify Delivery Person
- Delete Delivery Person

Classes:
- Subscriber
- Subscription
- DeliveryPerson
- DeliveryArea
- SubscriptionRate (RegularRate, SpecialRate)
- System
- Database
