∀ {α : Type u} {cmp : α → α → Ordering} [Std.TransCmp cmp] {β : Type v} {t : Std.DTreeMap.Raw α (fun x => β) cmp},
  t.WF →
    ∀ {k k' : α} [hi : Inhabited β] {f : β → β},
      Std.DTreeMap.Raw.Const.get! (Std.DTreeMap.Raw.Const.modify t k f) k' =
        if cmp k k' = Ordering.eq then (Option.map f (Std.DTreeMap.Raw.Const.get? t k)).get!
        else Std.DTreeMap.Raw.Const.get! t k'