Chapter 3, Problem 6E

Create a second NumberDisplay object with a limit of 60, and give it the name minutes. Call its increment method and note how the method calls are represented in the Terminal window. Imagine that the hours and minutes objects on the object bench represent the two NumberDisplay objects managed by a ClockDisplay object. In effect, you are now performing the role of the C1ockDisplay object. What should you do each time you call increment on minutes to decide whether it has rolled over and whether increment should therefore be called on the hours object?