∀ {α : Type u} {β : α → Type v} (m : Std.DHashMap.Internal.Raw₀ α β) [inst : BEq α] [inst_1 : Hashable α]
  [inst_2 : LawfulBEq α], (↑m).WF → ∀ {a : α} [inst_3 : Inhabited (β a)], m.get! a = m.getD a default