∀ {C : Type u_1} [inst : CategoryTheory.Category.{v_1, u_1} C] {D : Type u_2}
  [inst_1 : CategoryTheory.Category.{v_2, u_2} D] {K : CategoryTheory.GrothendieckTopology D}
  {G : CategoryTheory.Functor C D} [inst_2 : G.IsCoverDense K] [inst_3 : G.IsLocallyFull K]
  {ℱ ℱ' : CategoryTheory.Sheaf K (Type v)} (i : G.op.comp ℱ.val ≅ G.op.comp ℱ'.val),
  (CategoryTheory.Functor.IsCoverDense.Types.sheafIso i).hom.val =
    (CategoryTheory.Functor.IsCoverDense.Types.presheafIso i).hom