[dmytrish]

> If you had to build one from scratch, how would you do it?

I consider Jupyter notebooks to be a fascinating evolution of the terminal paradigm: their basic behavior is close enough to a terminal, but then you are free to rearrange, rerun, delete cells, you can have rich visualization and any type of browser content, you can save and restore sessions (notebooks), share them easily, access them over the network, detach from them, etc.