∀ {C : Type u_1} [inst : CategoryTheory.Category.{v_1, u_1} C] [inst_1 : CategoryTheory.Limits.HasPullbacks C] {X : C}
  (R S T : CategoryTheory.Over X) {Z : C} (h : T.left ⟶ Z),
  CategoryTheory.CategoryStruct.comp (CategoryTheory.MonoidalCategoryStruct.associator R S T).inv.left
      (CategoryTheory.CategoryStruct.comp
        (CategoryTheory.Limits.pullback.snd
          (CategoryTheory.CategoryStruct.comp (CategoryTheory.Limits.pullback.fst R.hom S.hom) R.hom) T.hom)
        h) =
    CategoryTheory.CategoryStruct.comp
      (CategoryTheory.Limits.pullback.snd R.hom (CategoryTheory.MonoidalCategoryStruct.tensorObj S T).hom)
      (CategoryTheory.CategoryStruct.comp (CategoryTheory.Limits.pullback.snd S.hom T.hom) h)