∀ {α : Type u} {β : α → Type v} {l : Std.DHashMap.Raw α β} {acc : Array ((a : α) × β a)},
  Std.DHashMap.Raw.fold (fun acc k v => acc.push ⟨k, v⟩) acc l =
    acc ++ (Std.DHashMap.Internal.toListModel l.buckets).toArray