often when I am developing systems code or RPC client code, I sit in a REPL and make repeated ad-hoc calls to various functions, building up various bits of state (I started using python long before Jupyter). I find this much more intuitive than writing code, compiling it, executing it, going back to the editor, changing the code, re-running it with something that loads a bunch of data, just so I can answer a question about the runtime behavior of the system I'm working with.