proposition: Lemma binds_one_3 : x = y -> a = b -> binds x a (y ~ b).
proof: Proof. clear. unfold binds. intros. simpl. left. congruence. Qed.
imports: Coq.FSets.FSets Coq.Lists.List Coq.Logic.Decidable Coq.Strings.String String Metalib.CoqFSetDecide Metalib.CoqListFacts Metalib.LibTactics Metalib.CoqFSetInterface Coq.Classes.Equivalence Coq.Classes.EquivDec Metalib.CoqEqDec