Domain\Billet\BilletRepository::pay PHP Метод

    public function pay($billet_id, Carbon $date)
    {
        $model = $this->model;
        $billet = $model->find($billet_id);
        if (!is_null($billet->discharge_date)) {
            throw new RepositoryException("You can't pay this billet");
        }
        $billet->discharge_date = $date->toDateString();
        $billet->save();
        return $billet;
    }