This chapter concentrated on the current status of Python and the process of change that was visible throughout the history of that language. We started with a discussion of how and why Python changes and described what the main results of that process are, including the differences between Python 2 and 3. We've learned how to reliably deal with those changes and learned some useful techniques that allow us to provide code that is compatible with various versions of Python and different versions of its libraries.
Then, we took a different look at the idea of changes in programming language. We've reviewed some of the popular alternative Python interpreters and discussed their main differences compared to default CPython implementation.
In the next chapter, we will describe modern ways of setting up repeatable and consistent development environments for Python...
