∀ {C : Type u₁} [inst : CategoryTheory.Category.{v₁, u₁} C] {D : Type u₂} [inst_1 : CategoryTheory.Category.{v₂, u₂} D]
  (e : C ≌ D) {X Y : D} (f : X ⟶ Y) {Z : D} (h : Y ⟶ Z),
  CategoryTheory.CategoryStruct.comp (e.functor.map (e.inverse.map f))
      (CategoryTheory.CategoryStruct.comp (e.counit.app Y) h) =
    CategoryTheory.CategoryStruct.comp (e.counit.app X) (CategoryTheory.CategoryStruct.comp f h)