proposition: Lemma uniq_cons_3 : uniq E -> x `notin` dom E -> uniq ((VarAsn B x a) :: E).
proof: Proof. clear. solve_uniq. Qed.
imports: Coq.FSets.FSets Coq.Lists.List Coq.Logic.Decidable Metalib.CoqFSetDecide Metalib.CoqListFacts Metalib.LibTactics Metalib.MetatheoryAtom Metalib.LibTactics