∀ {α : Type u} {cmp : α → α → Ordering} {β : Type v} {t : Std.DTreeMap α (fun x => β) cmp} [Std.TransCmp cmp]
  [inst : BEq α] [Std.LawfulBEqCmp cmp] {l : List (α × β)} {k : α},
  Std.DTreeMap.Const.get? (Std.DTreeMap.Const.insertMany t l) k =
    (List.findSomeRev?
          (fun x =>
            match x with
            | (a, b) => if cmp a k = Ordering.eq then some b else none)
          l).or
      (Std.DTreeMap.Const.get? t k)