HWChange Scenarios. The second phase involved the implementation of four
changes (Sec. 3.3) in the original HW system. Each change involved: (i) the
design improvement through refactoring and design patterns , (ii) the
design and implementation of new functionalities (comprising six new user cases) to
be included, (iii) the removal of one use case from the system, and (iv) the complete
removal of the design by contract concern.