[bobuk]

Looks like a fancy version of good old icecream. https://github.com/gruns/icecream

If you never heard about it, scroll to the bottom to https://github.com/gruns/icecream#icecream-in-other-language...

[creichenbach]

Neat. I built something similar but web-based for Java years ago: https://scg.unibe.ch/wiki/projects/DoodleDebug