∀ {X Y Z : AlgebraicGeometry.Scheme} (f : X ⟶ Z) (g : Y ⟶ Z) [H : AlgebraicGeometry.IsOpenImmersion f],
  Set.range ⇑(CategoryTheory.Limits.pullback.fst g f) =
    ↑((TopologicalSpace.Opens.map g.base).obj (AlgebraicGeometry.Scheme.Hom.opensRange f))