∀ {α : Type u} {cmp : α → α → Ordering} {β : Type v} {t : Std.DTreeMap.Raw α (fun x => β) cmp} [Std.TransCmp cmp],
  t.WF →
    ∀ {k k' : α} {f : Option β → Option β},
      cmp k k' = Ordering.eq →
        (k' ∈ Std.DTreeMap.Raw.Const.alter t k f ↔ (f (Std.DTreeMap.Raw.Const.get? t k)).isSome = true)