This exercise has no code. It is simply the exercise you complete to get your computer to run Python. You should follow these instructions as exactly as possible. For example, Mac OSX computers already have Python 2, so do not install Python 3 (or any Python).
If you do not know how to use PowerShell on Windows or the Terminal on OSX or “Bash” on Linux, then you need to go learn that first. I have included an abbreviated version of my book The Command Line Crash Course in the appendix. Go through that first and then come back to these instructions.