∀ {C : Type u} [inst : CategoryTheory.Category.{v, u} C] {X Y : AlgebraicGeometry.PresheafedSpace C} (f : X ⟶ Y)
  [H : AlgebraicGeometry.PresheafedSpace.IsOpenImmersion f] {Z : AlgebraicGeometry.PresheafedSpace C} (g : Y ⟶ Z)
  [hg : AlgebraicGeometry.PresheafedSpace.IsOpenImmersion g],
  AlgebraicGeometry.PresheafedSpace.IsOpenImmersion (CategoryTheory.CategoryStruct.comp f g)