You're probably thinking of http://pythontutor.com/ http://pythontutor.com/ for python. It's one of my absolute favorite instructional resources for any languag

You're probably thinking of http://pythontutor.com/ http://pythontutor.com/ for python. It's one of my absolute favorite instructional resources for any language. Birdseye[1] looks like it is trying to be a similar kind of thing for debugging Python, which is amazing. I don't know of anything for anything similar for Rust or anything with similar characteristics (C/++). [1] https://github.com/alexmojaki/birdseye https://github.com/alexmojaki/birdseye