For these exercises, we will be using Anaconda, a version of Python that comes packaged with useful libraries for working with natural language and scientific data.
To download Anaconda, follow this link and click the button for your operating system and Python 3.x (3.6 at the time of this writing). You want the 64-bit, graphical installer version.
After installation, to test that Anaconda is working correctly, type
$ python --version
in your terminal. If Anaconda is working, your output should look like this:
Python 3.6.4:: Anaconda 2.5.0 (64-bit)
Note that to get this output you may need to refresh your terminal by typing exec $SHELL in the prompt (including the $) or by closing and reopening the terminal.