∀ {X Y Z : AlgebraicGeometry.Scheme} (f : X ⟶ Y) (g : Y ⟶ Z) (U : Z.Opens),
  (TopologicalSpace.Opens.map f.base).obj ((TopologicalSpace.Opens.map g.base).obj U) =
    (TopologicalSpace.Opens.map (CategoryTheory.CategoryStruct.comp f g).base).obj U