∀ {C : Type u} [inst : CategoryTheory.Category.{v, u} C] {J : CategoryTheory.GrothendieckTopology C}
  {F G : CategoryTheory.Sheaf J (Type w)} (φ : F ⟶ G) [CategoryTheory.HasSheafify J (Type w)],
  CategoryTheory.Sheaf.IsLocallySurjective φ ↔ CategoryTheory.Epi φ