proposition: Lemma Forall2_one_eq : forall P x y, Forall2 P (x::nil) (y::nil) = P x y.
proof: Proof. Proof using. intros. extens. rewrite Forall2_cons_eq. rewrite* Forall2_nil_eq. Qed.
imports: Coq.Classes.Morphisms TLC(LibTactics LibLogic LibReflect LibOperation LibProd LibOption LibNat LibInt LibWf LibMonoid LibRelation)