∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] (x : C),
  CategoryTheory.CategoryStruct.comp
      (CategoryTheory.CategoryStruct.id ((CategoryTheory.Functor.id C).obj ((CategoryTheory.Functor.id C).obj x)))
      ((CategoryTheory.Iso.refl ((CategoryTheory.Functor.id C).comp (CategoryTheory.Functor.id C))).hom.app
        ((CategoryTheory.Functor.id C).obj x)) =
    (CategoryTheory.Iso.refl ((CategoryTheory.Functor.id C).comp (CategoryTheory.Functor.id C))).hom.app
      ((CategoryTheory.Functor.id C).obj x)