∀ {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} {ℱ : CategoryTheory.Functor Dᵒᵖ (Type v)} {ℱ' : CategoryTheory.Sheaf K (Type v)}
  [inst_2 : G.IsCoverDense K] [inst_3 : G.IsLocallyFull K] (α : G.op.comp ℱ ⟶ G.op.comp ℱ'.val) (X : Dᵒᵖ)
  (a : ℱ.obj (Opposite.op (Opposite.unop X))),
  (CategoryTheory.Functor.IsCoverDense.Types.presheafHom α).app X a =
    CategoryTheory.Functor.IsCoverDense.Types.appHom α (Opposite.unop X) a