∀ {α : Type u} {β : α → Type v} [inst : BEq α] [inst_1 : Hashable α] {m₁ m₂ : Std.DHashMap.Internal.Raw₀ α β}
  [inst_2 : LawfulBEq α],
  (↑m₁).WF →
    (↑m₂).WF → ∀ {k : α} {fallback : β k}, m₂.contains k = true → (m₁.inter m₂).getD k fallback = m₁.getD k fallback