∀ {C : Type u} [inst : CategoryTheory.Category.{v, u} C] [inst_1 : CategoryTheory.MonoidalCategory C] {W X Y Z : C},
  CategoryTheory.CategoryStruct.comp
      (CategoryTheory.MonoidalCategoryStruct.associator W X (CategoryTheory.MonoidalCategoryStruct.tensorObj Y Z)).hom
      (CategoryTheory.CategoryStruct.comp
        (CategoryTheory.MonoidalCategoryStruct.whiskerLeft W
          (CategoryTheory.MonoidalCategoryStruct.associator X Y Z).inv)
        (CategoryTheory.MonoidalCategoryStruct.associator W (CategoryTheory.MonoidalCategoryStruct.tensorObj X Y)
            Z).inv) =
    CategoryTheory.CategoryStruct.comp
      (CategoryTheory.MonoidalCategoryStruct.associator (CategoryTheory.MonoidalCategoryStruct.tensorObj W X) Y Z).inv
      (CategoryTheory.MonoidalCategoryStruct.whiskerRight (CategoryTheory.MonoidalCategoryStruct.associator W X Y).hom
        Z)