suffices h : IsClosed {f : 𝓒 U | MapsTo f U (closedBall 0 1)} by
  exact (isClosed_𝓗 hU).inter h
U : Set ℂ
Q : Set ℂ → Set ℂ
ι : Type u_1
l : Filter ι
hU : IsOpen U
⊢ IsClosed (𝓜 U)
U : Set ℂ
Q : Set ℂ → Set ℂ
ι : Type u_1
l : Filter ι
hU : IsOpen U
⊢ IsClosed {f | MapsTo f U (closedBall 0 1)}