∀ {C : Type u_1} [inst : CategoryTheory.Category.{v_1, u_1} C] {A : Type u_2} [inst_1 : AddMonoid A]
  [inst_2 : CategoryTheory.HasShift C A] (X : CategoryTheory.OppositeShift C A) (a b c : A) (h : a + b = c),
  (CategoryTheory.shiftFunctorAdd' (CategoryTheory.OppositeShift C A) a b c h).inv.app X =
    ((CategoryTheory.shiftFunctorAdd' C a b c h).hom.app (Opposite.unop X)).op