proposition: Lemma binds_subst : forall x2 v2 x1 v1 E1 E2, binds x1 v1 (E1 & x2 ~ v2 & E2) -> x1 <> x2 -> binds x1 v1 (E1 & E2).
proof: Proof. Proof using. introv H N. applys~ binds_remove H. Qed.
imports: TLC(LibTactics LibOption LibList LibProd LibLogic LibReflect)