proposition: Lemma Exists_last_eq : forall P l x, Exists P (l&x) = (P x \/ Exists P l).
proof: Proof. Proof using. intros. extens. rewrite Exists_app_eq. rewrite Exists_cons_eq. rewrite* Exists_nil_eq. Qed.
imports: Coq.Classes.Morphisms TLC(LibTactics LibLogic LibReflect LibOperation LibProd LibOption LibNat LibInt LibWf LibMonoid LibRelation)