z.sort(reverse=True)
z

The output of the above code is as follows:

[3, 2, 1]

If you need to do a reverse sort, you can just say reverse=True as an attribute, as a parameter in that sort function, and that will put it back to 3, 2, 1.

If you need to let that sink in a little bit, feel free to go back and read it a little bit more.