∀ (X : AlgebraicGeometry.Scheme) [inst : CompactSpace ↥X] (𝒰 : X.OpenCover)
  [∀ (i : 𝒰.I₀), AlgebraicGeometry.IsAffine (𝒰.X i)] (i : 𝒰.finiteSubcover.I₀),
  AlgebraicGeometry.IsAffine (𝒰.finiteSubcover.X i)