Yes, I was proposing it as a new feature, but only because I had no idea that it had been already implemented. As soon as I figured that out, I found the setting in the default prefs, but thanks for the detailed explanation :) It is slightly different from what I described above, but otherwise it's exactly what I've been missing.
It seems for some reason I'm not seeing any indentation highlighting, so I was not aware it ever existed. Forget about this thread.
If you're on line 3 (the "for" statement), the third indentation guide should be highlighted, because that line is indented at the same level. The algorithm should be something like:
Customer support service by UserEcho