∀ {X Y : AlgebraicGeometry.Scheme} (f : X ⟶ Y) [inst : AlgebraicGeometry.IsImmersion f]
  [AlgebraicGeometry.QuasiCompact f],
  CategoryTheory.IsPullback (AlgebraicGeometry.Scheme.Hom.toImage f) (AlgebraicGeometry.Scheme.Hom.liftCoborder f)
    (AlgebraicGeometry.Scheme.Hom.imageι f) (AlgebraicGeometry.Scheme.Hom.coborderRange f).ι