∀ {X Y Z : AlgebraicGeometry.Scheme} (𝒰 : Z.OpenCover) (f : X ⟶ Z) (g : Y ⟶ Z)
  (i :
    (AlgebraicGeometry.Scheme.Pullback.openCoverOfLeft (CategoryTheory.Precoverage.ZeroHypercover.pullback₁ f 𝒰) f
        g).I₀),
  CategoryTheory.Limits.HasPullback g (𝒰.f i)