∀ {C : Type u} [inst : CategoryTheory.Category.{v, u} C] [inst_1 : CategoryTheory.Preadditive C]
  [inst_2 : CategoryTheory.Limits.HasZeroObject C] {X : C} {K : CochainComplex C ℤ} {p q : ℤ} (f : K.X p ⟶ X) {n : ℤ}
  (h : p + n = q) (p' : ℤ) (hp' : p' + 1 = p) (hf : CategoryTheory.CategoryStruct.comp (K.d p' p) f = 0),
  ↑(CochainComplex.HomComplex.Cocycle.toSingleMk f h p' hp' hf) = CochainComplex.HomComplex.Cochain.toSingleMk f h