∀ {α : Type u} {x : BEq α} {x_1 : Hashable α} {β : Type v} [inst : EquivBEq α] [inst_1 : LawfulHashable α]
  [inst_2 : Inhabited β] (m m_1 : Std.ExtDHashMap α fun x => β),
  m = m_1 → ∀ (a a_1 : α), a = a_1 → Std.ExtDHashMap.Const.get! m a = Std.ExtDHashMap.Const.get! m_1 a_1