∀ {X : Type u_1} [t : TopologicalSpace X] {C D : Set X} [inst : Topology.RelCWComplex C D]
  (I J : (n : ℕ) → Set (Topology.RelCWComplex.cell C n)),
  D ∪ ⋃ n, ⋃ j, Topology.RelCWComplex.openCell n ↑j = D ∪ ⋃ n, ⋃ j, Topology.RelCWComplex.openCell n ↑j → I = J