Éric,
I know perfectly well that [].append is valid Python, but I don't think this is the clearest way to give an example of an object method. I think spelling [].append's meaning more explicitly would be better.

I'm also aware that there are tab problems all over the code base. I'm not suggesting a large cleanup. But I do think that in *example code* in the documentation, it wouldn't hurt to make the code idiomatically styled. After all, this is what people will copy-paste when writing new code.