∀ {α : Type u} {β : α → Type v} {cmp : α → α → Ordering} {t : Std.DTreeMap α β cmp} [Std.TransCmp cmp]
  {l : List ((a : α) × β a)} {k k' : α},
  cmp k k' = Ordering.eq →
    List.Pairwise (fun a b => ¬cmp a.fst b.fst = Ordering.eq) l →
      k ∈ List.map Sigma.fst l → ∀ {h' : k' ∈ t.insertMany l}, (t.insertMany l).getKey k' h' = k