So far you have been dealing with simple data. In general, you will need to work with data that has some internal structure. You will deal with that in this chapter.
In this chapter, you will keep working with the command line; examples are intended to be typed into the REPL, either locally or in some other shape (as seen in Chapter 1).
In this chapter, you will explore two concepts that will be fleshed out later: class (or type) and role. A class describes how objects (or instances) of that class behave and which attributes they contain; ...