Decidable equivalence for DHashMap

instance Std.DHashMap.instDecidableEquivOfLawfulBEq {α : Type u} {β : α → Type v} [BEq α] [LawfulBEq α] [Hashable α] [(k : α) → BEq (β k)] [∀ (k : α), LawfulBEq (β k)] (m₁ m₂ : DHashMap α β) : Decidable (m₁.Equiv m₂)