∀ {C : Type u_1} {D : Type u_2} [inst : CategoryTheory.Category.{v_1, u_1} C]
  [inst_1 : CategoryTheory.Category.{v_2, u_2} D] {A : Type u_5} [inst_2 : AddMonoid A]
  [inst_3 : CategoryTheory.HasShift D A] (F : CategoryTheory.SingleFunctors C D A) (a : A) (X : C),
  (F.shiftIso 0 a a ⋯).hom.app X = (CategoryTheory.shiftFunctorZero D A).hom.app ((F.functor a).obj X)