Jhack, thanks so much. You write simple, clear, basic instructions that even I can follow, and I was able to strip the DRM from some of my
Amazon books using Python. (Most of them I don't bother with, but I have a few that I was thrilled to be able to buy and really don't want to take the chance of Amazon pulling them!)
I never did figure out how to strip it in Calibre, but I guess it doesn't matter.