∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] {F G : CategoryTheory.Functor C (Type u_3)} ⦃X Y : C⦄
  (f : X ⟶ Y),
  (CategoryTheory.CategoryStruct.comp (F.map f) fun x => Sum.inl x) =
    CategoryTheory.CategoryStruct.comp (fun x => Sum.inl x) ((CategoryTheory.FunctorToTypes.coprod F G).map f)