simp
β : Type u_1
inst✝ : Encodable β
e : ℕ
this : e.unpair.2 < e + 1
⊢ decode (e + 1) = mapM' decode (Denumerable.ofNat (List ℕ) (e + 1))
β : Type u_1
inst✝ : Encodable β
e : ℕ
this : e.unpair.2 < e + 1
⊢ (Seq.seq (Option.map (fun x x_1 => x :: x_1) (decode e.unpair.1)) fun x => decode e.unpair.2) =
    (decode e.unpair.1).bind fun __do_lift =>
      (mapM' decode (Denumerable.ofNat (List ℕ) e.unpair.2)).bind fun __do_lift_1 => some (__do_lift :: __do_lift_1)