∀ (C : Type u_2) [inst : CategoryTheory.Category.{u_1, u_2} C] [inst_1 : CategoryTheory.MonoidalCategory C]
  (X : CategoryTheory.Comon C),
  Opposite.op { hom := (CategoryTheory.CategoryStruct.id X).hom.op, isMonHom_hom := ⋯ } =
    CategoryTheory.CategoryStruct.id (Opposite.op X.ComonToMonOpOpObj)