Exclamation point LS is a shorthand. It's very useful for, I think it's also available as percent as X. You can do exclamation point LS to get do a directory listing just to see what is in the directory or you can do paying a machine to see if it's all directly from your notebook. So this is a quick and word with dirty way of running command line commands without having to leave your notes. And then another one I want to mention is just exclamation point and then the shell command. This gets you just a very quick and dirty answer to like orders of magnitude is the same level or should I be doing things differently?