∀ {α : Type u} {x : BEq α} {x_1 : Hashable α} {β : Type v} {m : Std.DHashMap α fun x => β} [EquivBEq α]
  [LawfulHashable α] {p : α → β → Bool},
  m.all p = false ↔ ∃ a, ∃ (h : a ∈ m), p (m.getKey a h) (Std.DHashMap.Const.get m a h) = false