∀ {C : Type u₁} [inst : CategoryTheory.Category.{v₁, u₁} C] [inst_1 : CategoryTheory.MonoidalCategory C] {D : Type u₂}
  [inst_2 : CategoryTheory.Category.{v₂, u₂} D] [inst_3 : CategoryTheory.MonoidalCategory.MonoidalLeftAction C D]
  {M : C} [inst_4 : CategoryTheory.MonObj M] (X : D) [inst_5 : CategoryTheory.ModObj M X],
  CategoryTheory.CategoryStruct.comp
      (CategoryTheory.MonoidalCategory.MonoidalLeftActionStruct.actionHomRight M CategoryTheory.ModObj.smul)
      CategoryTheory.ModObj.smul =
    CategoryTheory.CategoryStruct.comp
      (CategoryTheory.MonoidalCategory.MonoidalLeftActionStruct.actionAssocIso M M X).inv
      (CategoryTheory.CategoryStruct.comp
        (CategoryTheory.MonoidalCategory.MonoidalLeftActionStruct.actionHomLeft CategoryTheory.MonObj.mul X)
        CategoryTheory.ModObj.smul)