∀ {α : Type u} {x : BEq α} {x_1 : Hashable α} {β : Type v} {m₁ m₂ : Std.ExtDHashMap α fun x => β} [inst : EquivBEq α]
  [inst_1 : LawfulHashable α],
  (∀ (k : α) (hk : k ∈ m₁) (hk' : k ∈ m₂), m₁.getKey k hk = m₂.getKey k hk') →
    (∀ (k : α), Std.ExtDHashMap.Const.get? m₁ k = Std.ExtDHashMap.Const.get? m₂ k) → m₁ = m₂