∀ {k G : Type u} [inst : CommRing k] [inst_1 : Group G] (A : Rep k G),
  CategoryTheory.CategoryStruct.comp (groupCohomology.cochainsIso₂ A).hom (groupCohomology.d₂₃ A) =
    CategoryTheory.CategoryStruct.comp ((groupCohomology.inhomogeneousCochains A).d 2 3)
      (groupCohomology.cochainsIso₃ A).hom