- Design by Contract
                        -  Eiffel's implementation of design by contract
                        - preconditions, postconditions and class invariants; use of assertions
                        - Design by contract in analysis and its manifestation in implementation
                        - The issue of Seamlessness
                        Reading: Chapter 2 and 11 of Bertrand Meyer's book on "Object Oriented Software
                        Construction". www.eiffel.com has posted a nice article on design by contract.

                        Implementation Exercise 2. Exercises will soon get queued up. So have you
                        finished the first exercise?! Focus on design aspects, write only the skeletal
                        code, since at this point of time, our interest is in interfaces and interobject
                        interactions through them.