fact: Axiom uniq_app_4 : uniq E -> uniq F -> disjoint E F -> uniq (E ++ F).
imports: Coq.FSets.FSets Coq.Lists.List Coq.Logic.Decidable Metalib.CoqFSetDecide Metalib.CoqListFacts Metalib.AssocList Metalib.MetatheoryAtom Metalib.LibTactics