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Exercise 8.4
The interface ITaxable

For the purpose of this exercise you are given a couple of very simple classes called Bus and House. Class Bus specializes the class Vehicle. Class House specializes the class FixedProperty. All the classes are here.

First in this exercise, program an interface ITaxable with a parameterless operation TaxValue. The operation should return a decimal number.

Next, program variations of class House and class Bus which implement the interface ITaxable. Feel free to invent the concrete taxation of houses and busses. Notice that both class House and Bus have a superclass, namely FixedProperty and Vehicle, respectively. Therefore it is essential that taxation is introduced via an interface.

Demonstrate that taxable house objects and taxable bus objects can be used together as objects of type ITaxable.