∀ {C : Type u_1} {D : Type u_2} {E : Type u_3} {E' : Type u_4} [inst : CategoryTheory.Category.{v_1, u_1} C]
  [inst_1 : CategoryTheory.Category.{v_2, u_2} D] [inst_2 : CategoryTheory.Category.{v_3, u_3} E]
  [inst_3 : CategoryTheory.Category.{v_4, u_4} E'] {A : Type u_5} [inst_4 : AddMonoid A]
  [inst_5 : CategoryTheory.HasShift D A] [inst_6 : CategoryTheory.HasShift E A] [inst_7 : CategoryTheory.HasShift E' A]
  (F : CategoryTheory.SingleFunctors C D A) (G : CategoryTheory.Functor D E) (G' : CategoryTheory.Functor E E')
  [inst_8 : G.CommShift A] [inst_9 : G'.CommShift A] (a : A) (x : C),
  ((F.postcompPostcompIso G G').inv.hom a).app x =
    CategoryTheory.CategoryStruct.id (G'.obj (G.obj ((F.functor a).obj x)))