∀ {H : Type x} [inst : TopologicalSpace H] [inst_1 : AddCommGroup H] [inst_2 : PartialOrder H] [IsOrderedAddMonoid H]
  [ContinuousAdd H] {c a : H},
  Filter.map (fun x => c + x) (nhdsWithin a (Set.Ioi a)) = nhdsWithin (c + a) (Set.Ioi (c + a))