Extract expression is such a common refactoring, happy to see support for it. I'm even more curious to see now if there are going to be more advanced refactoring possible. A List.map, to for loop, and back refactoring would be such a great thing to have in how I program.

Only thing that would go on my OCD nerve, is the lack of an empty newline when the show_markup function is extracted. Kind of "common sense" when writing top level bindings to leave some breathing room between them.