∀ {C : Type u} [inst : CategoryTheory.Category.{v, u} C] [inst_1 : CategoryTheory.Abelian C] {K L : CochainComplex C ℤ}
  {n : ℤ}
  [inst_2 :
    CategoryTheory.Localization.HasSmallLocalizedShiftedHom (HomologicalComplex.quasiIso C (ComplexShape.up ℤ)) ℤ K L]
  [inst_3 : HasDerivedCategory C] (x : CochainComplex.HomComplex.Cocycle K L n),
  (CategoryTheory.Localization.SmallShiftedHom.equiv (HomologicalComplex.quasiIso C (ComplexShape.up ℤ))
        DerivedCategory.Q)
      (CochainComplex.HomComplex.CohomologyClass.mk x).toSmallShiftedHom =
    CategoryTheory.ShiftedHom.map (CochainComplex.HomComplex.Cocycle.equivHomShift.symm x) DerivedCategory.Q