∀ {C : Type u} [inst : CategoryTheory.Category.{v, u} C] [inst_1 : CategoryTheory.CartesianMonoidalCategory C] (X : C),
  CategoryTheory.CategoryStruct.comp (CategoryTheory.MonoidalCategoryStruct.leftUnitor X).inv
      (CategoryTheory.SemiCartesianMonoidalCategory.fst (CategoryTheory.MonoidalCategoryStruct.tensorUnit C) X) =
    CategoryTheory.SemiCartesianMonoidalCategory.toUnit X