The editor was used at David Beazley's talk [1] "Die Threads" at the EuroPython 2018 by live coding how threading in Python could look like [2].
David's talks always have these funky looking editors.
But here's one of the famous ones on GIL. https://youtu.be/Obt-vMVdM8s
Beware though, his talks are known to be devastating to the programmer, resulting in serious head injuries, trauma, headaches and other fun stuff.