∀ {C : Type u} [inst : CategoryTheory.Category.{v, u} C]
  (F : CategoryTheory.Pseudofunctor (CategoryTheory.LocallyDiscrete Cᵒᵖ) CategoryTheory.Cat)
  {J : CategoryTheory.GrothendieckTopology C} [F.IsPrestack J] {S : C}, ∀ R ∈ J S, F.IsPrestackFor R.arrows