Destructors in Hierarchies
	• Destructors are invoked at the end of the lifetime of an object. • Destructors are invoked in the opposite order from which their constructors are invoked. • This means that the derived class destructor is invoked before its base class destructor. • If there are indirect base classes, this sequence continues until the furthest base class destructor is invoked. • A derived class destructor is guaranteed that its base class members are still available for use.