Oh really guys...
If you want to know what it does, simply read the expression.
It's just a few lines.
Besides, everything is stated in the OT.

And if you still don't get it, simply try it out. If you don't play Garry's Mod, you won't need it. And if you play Garry's Mod, it will be pretty easy to copy&paste the code in the e2 editor.