∀ {X Y Z : AlgebraicGeometry.LocallyRingedSpace} (f : X ⟶ Z) (g : Y ⟶ Z)
  [H : AlgebraicGeometry.LocallyRingedSpace.IsOpenImmersion f],
  CategoryTheory.Limits.ReflectsLimit (CategoryTheory.Limits.cospan f g)
    AlgebraicGeometry.LocallyRingedSpace.forgetToSheafedSpace