∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] {D : Type u_4}
  [inst_1 : CategoryTheory.Category.{u_3, u_4} D] {F : CategoryTheory.Functor Cᵒᵖ D} {G : CategoryTheory.Functor Dᵒᵖ C}
  (a : F.rightOp ⊣ G) (X : D),
  CategoryTheory.CategoryStruct.comp (G.rightOp.map ((CategoryTheory.NatTrans.unop a.counit).app X))
      ((CategoryTheory.NatTrans.op a.unit).app (G.rightOp.obj X)) =
    CategoryTheory.CategoryStruct.id (G.rightOp.obj X)