detect laptop open/close from within Python?

[Skip Montanaro]

I'm going through a bout of RSI problems with my wrists, so klst night
I refreshed an old typing watcher program I wrote a couple decades ago
(there's a comment about Python 1.4 in the code!):

https://github.com/smontanaro/python-bits/blob/master/watch.py

It's far from perfect and I'm sure miles behind more modern stuff, but
it does the trick for me.

I noticed a feww minutes ago that when I opened my laptop it
immediately locked the screen. It would be nice to get notified of
open/close events on the laptop. Any idea if there is a signal I can
catch (Ubuntu 17.10) or a Tk event I can respond to?

Thx,

Skip