{X Y : AlgebraicGeometry.Scheme} →
  (f : X ⟶ Y) →
    {x y : ↥X} →
      x = y →
        (CategoryTheory.Arrow.mk (AlgebraicGeometry.Scheme.Hom.stalkMap f x) ≅
          CategoryTheory.Arrow.mk (AlgebraicGeometry.Scheme.Hom.stalkMap f y))