private function processImportRow(&$row)
    {
        // Get the model to represent this row.
        $model = $this->lookupModel($row);

        // Assign values to the model.
        foreach ($row as $key => $value) {
            if (empty($model->getKey()) || $model->$key !== $value) {
                $model->$key = $value;
            }
        }

        $model->save();

        $this->progress_bar->advance();
    }