∀ {α : Type u} [inst : BEq α] [inst_1 : Hashable α] {β : Type v} {m : Std.DHashMap.Raw α fun x => β}
  [inst_2 : EquivBEq α] [LawfulHashable α] {k k' : α} {f : β → β},
  m.WF →
    (Std.DHashMap.Raw.Const.modify m k f).getKey? k' =
      if (k == k') = true then if k ∈ m then some k else none else m.getKey? k'