∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] {D : Type u_4}
  [inst_1 : CategoryTheory.Category.{u_3, u_4} D] [inst_2 : IsEmpty C] (F G : CategoryTheory.Functor C D) {X Y : C}
  (f : X ⟶ Y),
  CategoryTheory.CategoryStruct.comp (F.map f) (isEmptyElim Y).hom =
    CategoryTheory.CategoryStruct.comp (isEmptyElim X).hom (G.map f)