∀ {C : Type u} [inst : CategoryTheory.Category.{v, u} C] [inst_1 : CategoryTheory.CartesianMonoidalCategory C]
  {X Y : C},
  CategoryTheory.CartesianMonoidalCategory.lift (CategoryTheory.SemiCartesianMonoidalCategory.fst X Y)
      (CategoryTheory.SemiCartesianMonoidalCategory.snd X Y) =
    CategoryTheory.CategoryStruct.id (CategoryTheory.MonoidalCategoryStruct.tensorObj X Y)