∀ {X Y : AlgebraicGeometry.Scheme} (f : X ⟶ Y) [AlgebraicGeometry.LocallyQuasiFinite f]
  [AlgebraicGeometry.QuasiCompact f] (x : ↥Y),
  AlgebraicGeometry.IsFinite (AlgebraicGeometry.Scheme.Hom.fiberToSpecResidueField f x)