Prefactoring: Extreme Abstraction, Extreme Separation, Extreme Readability

SAM ASKS THAT THE SYSTEM KEEP TRACK OF CUSTOMER ADDRESSES . Addresses involve Zip Codes. ^[*] We determine how to verify the Zip Codes. We also examine ways to keep track of the information flowing through the Zip Code verification interfaces.

^[*] As an example of the difficulty of keeping consistent ("Consistency is Simplicity"), the United States Postal Service uses ZIP Code, while the O'Reilly stylesheet uses Zip Code.