fact: Axiom uniq_cons_3 : uniq E -> ~ In x (dom E) -> uniq ((x, a) :: E).
imports: Coq.FSets.FSets Coq.Lists.List Coq.Logic.Decidable Metalib.CoqFSetDecide Metalib.CoqListFacts Metalib.AssocList Metalib.MetatheoryAtom Metalib.LibTactics