(a : a_part) (b : b_part a) := Eval simpl in forall x y z m1 m2, @' a b x y z m1 m2.
Require Import Category.Core Functor.Core NaturalTransformation.Core. Require Import Pseudofunctor.Core. Require Import Category.Morphisms FunctorCategory.Morphisms. Require Import Functor.Composition.Core. Require Import NaturalTransformation.Composition.Core NaturalTransformation.Composition.Laws. Require Import NaturalTransformation.Identity.