∀ {X : AlgebraicGeometry.Scheme} {x : ↥X},
  AlgebraicGeometry.Scheme.Hom.appTop (X.fromSpecStalk x) =
    CategoryTheory.CategoryStruct.comp (X.presheaf.germ ⊤ x trivial)
      (CategoryTheory.CategoryStruct.comp (AlgebraicGeometry.Scheme.ΓSpecIso (X.presheaf.stalk x)).inv
        ((AlgebraicGeometry.Spec (X.presheaf.stalk x)).presheaf.map (CategoryTheory.homOfLE ⋯).op))