Because I do things on paper (as the 6 white boards in my home office have other important things on them. . .actual code I was writing and debugging) and things wind up looking like this:

My awful code map

My code map which uses most of the colors of pen I have on my desk

Yeah. We’ll not talk about that actual code in idl and it’s amazing abuse of if and where statements. Why write a properly laid out code when you’re an astronomer and an electronic bludgeon can get the job done?