I often like to write out programs by hand (in some sort of pseudocode or whatever language I'm currently using) on "paper", except that "paper" is GoodNotes on an iPad Pro with an Apple Pencil. The benefit is that I can move things around after I write them. So, I can insert lines, indent or un-indent blocks, or move code into a subroutine. I can also easily add little diagrams. It's really opens up a new way of thinking! It's gotten to the point where when I'm at a whiteboard, I have the urge to rearrange stuff minority-report-style, until I remember that it's not a huge iPad.