No way to "start again"?

[benjohnbarnes]

I'm not sure if there is a way to start again? With the first function example, we accidentally trashed the code and couldn't work out how to get it back. I think in the end I guessed what the function syntax would probably be and wrote it.

I'd suggest a prominent "Restart" button, and on first use, explain that you can "Undo" the "Restart" if you wish.