> RG's use of "correct" doesn't mean that it's ok for a program to return "2+2=5" which is "better" than "2+2=4". But it means it's ok to occasionally return N

> RG's use of "correct" doesn't mean that it's ok for a program to return "2+2=5" which is "better" than "2+2=4". But it means it's ok to occasionally return Null, instead of of a guaranteed 4.