I love having a shell. When I want to know what a single line of code will do, I don't want to add print statements to code just to see what's going to happen. Bitlash is an arduino interpreter, so you can send individual commands to your arduino. I haven't used it yet, but once I get back into arduino development, it will be on my to learn list. It may be helpful for students to be able to run individual lines of code. Or I'll just have them write extensive test benches to test their code. Maybe both?