code: public function payout() {
      if (!$this->payout_id) { throw new GoCardless_ClientException("Cannot fetch payout for a bill that has not been paid out"); }
      return GoCardless_Payout::find_with_client($this->client, $this->payout_id);
    }
docs: Fetch the payout for a bill, if a payout_id is recorded
  @return object A GoCardless_Payout object representing the payout