If you look at any of the sample applications, you'll find:

public partial class VocabularyPage : HealthServicePage

The HealthServicePage does a lot for you, but it has the disadvantage of requiring you to use that page as a base class. In PB3, we've opened up the classes that HealthServicePage uses so that you can easily use them in your own base class.

The best example on how to use those classes is contained in the HealthServicePage itself, which you can find here.