If you thought that the if-else was great, there is even more to that structure for even more fun!
If this video is causing you issues, here is a copy on YouTube: https://youtu.be/v5D6dq6d5r8 (please, do not share)
One interesting use of the "return" command is to stop a script before the end. This means that if you got a script that merges everything, and you would rather not merge the layers, you can add a "return" command before the "Merge" command instead of deleting it.
Look at some scripts of mine, and see where I have used the if-elif-else structure.
The forum thread is here.