∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] [inst_1 : CategoryTheory.CartesianMonoidalCategory C]
  (X Y : C) {X_1 Y_1 : CategoryTheory.Over X} (g : X_1 ⟶ Y_1),
  CategoryTheory.CategoryStruct.comp (CategoryTheory.MonoidalCategoryStruct.whiskerRight g.left Y)
      (CategoryTheory.Over.mk (CategoryTheory.MonoidalCategoryStruct.whiskerRight Y_1.hom Y)).hom =
    (CategoryTheory.Over.mk (CategoryTheory.MonoidalCategoryStruct.whiskerRight X_1.hom Y)).hom