∀ {α : Type u} {β : α → Type v} (m : Std.DHashMap.Internal.Raw₀ α β) [inst : BEq α] [inst_1 : Hashable α] [EquivBEq α]
  [LawfulHashable α], (↑m).WF → ∀ {k : α}, Array.find? (fun x => x.fst == k) (↑m).toArray = none ↔ m.contains k = false