∀ {α : Type u_1} {β : Type u_2} [inst : TopologicalSpace α] [inst_1 : TopologicalSpace β] {f : α → β} {s : Set α}
  {t : Set β}, Set.MapsTo f s t → (∀ x ∈ closure s, ContinuousWithinAt f s x) → Set.MapsTo f (closure s) (closure t)