Feat: Error on undefined function
Fix: All ids are now prefix to prevent native var clashes.
This was already done on it2, but now also in it0 and it1.
Redid it2 to match.
Fix: generate-recipes would not complain on missing exp.
Fix: Adds documentation and test for not
Chore: __check helper function for ease of use in it0, it1.
Chore: some reordering to match more between iterations.
