∀ {α : Type u} [inst : BEq α] [inst_1 : Hashable α] {β : Type v} {m₁ m₂ : Std.DHashMap.Internal.Raw₀ α fun x => β}
  [EquivBEq α] [LawfulHashable α] [inst_4 : Inhabited β],
  (↑m₁).WF →
    (↑m₂).WF →
      ∀ {k : α},
        Std.DHashMap.Internal.Raw₀.Const.get! (m₁.diff m₂) k =
          if m₂.contains k = true then default else Std.DHashMap.Internal.Raw₀.Const.get! m₁ k