∀ {C : Type u_1} [inst : CategoryTheory.Category.{u_4, u_1} C] {D : Type u_3}
  [inst_1 : CategoryTheory.Category.{u_2, u_3} D] [inst_2 : CategoryTheory.MonoidalCategory D]
  (A : CategoryTheory.Mon (CategoryTheory.Functor C D)),
  CategoryTheory.CategoryStruct.comp CategoryTheory.MonObj.one
      {
        app := fun x =>
          CategoryTheory.CategoryStruct.id
            (((CategoryTheory.Monoidal.MonFunctorCategoryEquivalence.functor.comp
                        CategoryTheory.Monoidal.MonFunctorCategoryEquivalence.inverse).obj
                    A).X.obj
              x),
        naturality := ⋯ } =
    CategoryTheory.MonObj.one