∀ {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 → ∀ {k a : α} [inst_3 : Inhabited (β a)], (m.erase k).get! a = if (k == a) = true then default else m.get! a