In this chapter, you learned how to maximize code reuse by writing code capable of working with objects of different types. We took advantage of duck typing in Python and JavaScript. We worked with interfaces and generics in C#. We created classes capable of working with one and two constrained generic types.

Now that you learned how to work with duck typing and generics, we are ready to organize complex object-oriented code in Python, JavaScript, and C#, which is the topic of the next chapter.