∀ {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 a : α} {v : β k}, (m.insert k v).contains a = (k == a || m.contains a)