proposition: Lemma VI : [the functor of G \o idfun] ~> F -> G ~> F.
proof: Proof. move=> [s [] [GFs]]. apply: (@Nattrans.Pack [the functor of G] F _ (Nattrans.Class (isNatural.Axioms_ _ _ _))). exact: GFs. Qed.
imports: mathcomp(all_ssreflect) HB(structures) monae_lib hierarchy monad_lib