In this chapter, you learned how to declare and combine multiple blueprints to generate a single instance. We worked with multiple inheritance of classes in Python. You also learned how to transform a base class to an abstract base class. We declared interfaces in C#. Then, we implemented them with different classes. We also combined interfaces with classes to take advantage of multiple inheritance in C#.

We took advantage of the flexibility of JavaScript that allowed us to add properties and methods to an existing object. We combined constructor functions with composition to generate all the necessary blueprints for our application without creating complex functions that emulate multiple inheritance in a language that wasn't designed with this feature in mind.

Now that we have learned about interfaces, multiple inheritance and composition, we are ready to work with duck typing and generics, which is the topic of the next chapter.