Notes on Section 15.4
	Two files: event.h and iceCream.cpp
	Some small improvements made and stored in

	Review of virtual functions.
		A C++ idea
		Assumed by humans and the UML.

	UML -- Classes
		how to show a priority_queue?

	UML -- Interactions

	Books code seems to work ok.

	Manual OO Simulation: each person plays the part of an object.
		I'll be the object randomizer and the main program.

	If time:
		In groups.
			Each group needs a person to be theStore.
			Each group needs a person to be theSimulation.
			Each group needs several people to be events.

Next: Maps and (extra) hash_maps