fact: Definition key (s: Prog): option Key := match s with | put _ k _ _ => Some k | get _ k _ => Some k | skip _ => None | fault _ => None end.
imports: Coq(FunctionalExtensionality Arith Lia) Coq(Arith.Peano_dec Arith.Compare_dec) Coq(Relations.Relation_Operators) Coq(List) Chapar(Predefs)