∀ {C : Type u₁} [inst : CategoryTheory.Category.{v₁, u₁} C] {D : Type u₂} [inst_1 : CategoryTheory.Category.{v₂, u₂} D]
  {e f g : C ≌ D} (α : f.functor ⟶ e.functor) (β : g.functor ⟶ f.functor) {Z : C ≌ D} (h : Z ⟶ g),
  CategoryTheory.CategoryStruct.comp h (CategoryTheory.Equivalence.mkHom (CategoryTheory.CategoryStruct.comp β α)) =
    CategoryTheory.CategoryStruct.comp (CategoryTheory.CategoryStruct.comp h (CategoryTheory.Equivalence.mkHom β))
      (CategoryTheory.Equivalence.mkHom α)