∀ {α : Type u_2} {β : Type u_3} {G : Type u_4} [inst : TopologicalSpace α] [inst_1 : AddGroup G]
  [inst_2 : AddAction G α] [ContinuousConstVAdd G α] [inst_4 : TopologicalSpace β] {f : β → α} {b : β} {s : Set β}
  (c : G), ContinuousWithinAt (fun x => c +ᵥ f x) s b ↔ ContinuousWithinAt f s b