proposition: Lemma Exists_last : forall P l x, Exists P l -> P x -> Exists P (l&x).
proof: Proof. Proof using. intros. rewrite* Exists_last_eq. Qed.
imports: Coq.Classes.Morphisms TLC(LibTactics LibLogic LibReflect LibOperation LibProd LibOption LibNat LibInt LibWf LibMonoid LibRelation)