∀ {α : Type u} [inst : BEq α] [inst_1 : Hashable α] (m : Std.DHashMap.Internal.Raw₀ α fun x => Unit) [EquivBEq α]
  [LawfulHashable α],
  (↑m).WF →
    ∀ {l : List α} {k : α},
      Std.DHashMap.Internal.Raw₀.Const.get? (↑(Std.DHashMap.Internal.Raw₀.Const.insertManyIfNewUnit m l)) k =
        if m.contains k = true ∨ l.contains k = true then some () else none