∀ {C : Type u} [inst : CategoryTheory.Category.{v, u} C] {D : Type u_1} [inst_1 : CategoryTheory.Category.{v_1, u_1} D]
  (X : CategoryTheory.Comma (CategoryTheory.Functor.id (CategoryTheory.Functor C D)) (CategoryTheory.Functor.const C)),
  (CategoryTheory.WithTerminal.equivComma.counitIso.inv.app X).right = CategoryTheory.CategoryStruct.id X.right