∀ {α : Type u} [inst : BEq α] [inst_1 : Hashable α] {β : Type v} (m : Std.DHashMap.Internal.Raw₀ α fun x => β)
  [EquivBEq α] [LawfulHashable α], Array.map Prod.fst (Std.DHashMap.Raw.Const.toArray ↑m) = (↑m).keysArray