Printers do it without wrinkling the sheets. Procrastinators will do it when they get around to it. Proctologists do it in the end. Professors do it by the book. Professors forget to do it.
Programmers do it depth-first.
Programmers do it routinely. Programmers do it with Unix. Programmers do it with bugs. Programs do it in loops. Psychiatrists do it like crazy.