fact: Definition nat_of := fun (x : atom) => x.
imports: Coq.Arith.Arith Coq.Arith.Max Coq.Classes.EquivDec Coq.Lists.List Coq.Structures.Equalities Coq.FSets.FSets Metalib.CoqListFacts Metalib.FSetExtra Metalib.FSetWeakNotin Metalib.LibTactics Lia