Ch3 - Add initial equality test

Chapter 3: Equality for All, page 16
Ch3 - Add fake implementation for equality

Chapter 3: Equality for All, page 16
Ch3 - Expand equality test with second example

Chapter 3: Equality for All, page 16
Ch3 - Generalize equality implementation to work for all examples

Chapter 3: Equality for All, page 17
Ch4 - Make multiplication test more 'speaking'

Chapter 4: Privacy, pages 19-20
Ch4 - Reduce coupling between tests and code

Chapter 4: Privacy, page 20