∀ {X : Type u} [inst : TopologicalSpace X] {α : Type u_1} {F : Filter α} {u : α → X} {x : X} {ι : Sort u_3}
  {p : ι → Prop} {s : ι → Set X},
  (nhds x).HasBasis p s → (MapClusterPt x F u ↔ ∀ (i : ι), p i → ∃ᶠ (a : α) in F, u a ∈ s i)