∀ (C : Type u_4) (D : Type u_2) [inst : CategoryTheory.Category.{u_3, u_4} C]
  [inst_1 : CategoryTheory.MonoidalCategory C] [inst_2 : CategoryTheory.Category.{u_1, u_2} D]
  [inst_3 : CategoryTheory.MonoidalCategory.MonoidalRightAction Cᴹᵒᵖ D] (c : C) (d : D),
  CategoryTheory.MonoidalCategory.MonoidalRightActionStruct.actionHomLeft (CategoryTheory.CategoryStruct.id d)
      { unmop := c } =
    CategoryTheory.CategoryStruct.id
      (CategoryTheory.MonoidalCategory.MonoidalRightActionStruct.actionObj d { unmop := c })