I presume this doesn't need a news entry, but I am happy to added one if necessary.

Following the changes proposed in #25479, I would like a little more time on this PR before review (no point commenting on exactly the same things).

OK, say when done.

@terryjreedy I think this is ready now. I would appreciate your particular scrutiny of where I have added an explicit check for is (not) None, as I had to revert a few because they caused issues during testing (despite me thinking I checked they were safe...).

Can you describe the 'issues'? Could you have uncovered a bug? Or are you really convinced that your initial thought was wrong?

Sorry, just things like passing a blank string to tkinter and so getting an error. This was a regression with my change (a blank string would be treated as false but my is not None would evaluate to true) and has been reverted.

Given that it is highly unlikely this is going to be merged (at least in the current form), I am closing this PR. I will leave the issue on bpo open for now.

Yes, leave issue open. My quick review is that I eventually want most but not all of the changes. (In particular, "Return xyz." is a legal docstring.) Some of the changes I would like one type at a time. There is an existing issue with more tests that is probably about ready to merge once I review it. But working on shell indents and sidebar now. So wait until I ask for something in particular.