∀ {X Y S : AlgebraicGeometry.Scheme} (sX : X ⟶ S) (sY : Y ⟶ S) [inst : AlgebraicGeometry.IsIntegral X]
  [inst_1 : AlgebraicGeometry.LocallyOfFiniteType sY]
  (f : { f // f.compHom sY = AlgebraicGeometry.Scheme.Hom.toRationalMap sX }),
  ((AlgebraicGeometry.Scheme.PartialMap.ofFromSpecStalk sX sY ↑⟨(↑f).fromFunctionField, ⋯⟩ ⋯).compHom
        sY).toRationalMap =
    (AlgebraicGeometry.Scheme.Hom.toPartialMap sX).toRationalMap