∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] [inst_1 : CategoryTheory.MonoidalCategory C]
  {R S : CategoryTheory.Mon C} (P : Bimod R S),
  CategoryTheory.CategoryStruct.comp (CategoryTheory.MonoidalCategoryStruct.whiskerRight P.actRight (Bimod.regular S).X)
      P.actRight =
    CategoryTheory.CategoryStruct.comp
      (CategoryTheory.CategoryStruct.comp
        (CategoryTheory.MonoidalCategoryStruct.associator P.X S.X (Bimod.regular S).X).hom
        (CategoryTheory.MonoidalCategoryStruct.whiskerLeft P.X (Bimod.regular S).actLeft))
      P.actRight