∀ {α : Type u_1} {inst : DecidableEq α} [inst_1 : DecidableEq α] {δ : α → Sort u_2} (m : Multiset α) (a : α)
  (b b_1 : δ a),
  b = b_1 →
    ∀ (f f_1 : (a : α) → a ∈ m → δ a),
      f = f_1 → ∀ (a' : α) (a_1 : a' ∈ a ::ₘ m), Multiset.Pi.cons m a b f a' a_1 = Multiset.Pi.cons m a b_1 f_1 a' a_1