public function saveSubset($subset)
    {
        $changes = $subset . 'Changes';
        if ($this->$changes === true) {
            if (!defined('JSON_PRETTY_PRINT')) {
                $json = json_encode($this->$subset);
            } else {
                $json = json_encode($this->$subset, JSON_PRETTY_PRINT);
            }
            $subsetStoragePath = $this->storagePath . DIRECTORY_SEPARATOR . $subset . '.json';
            file_put_contents($subsetStoragePath, $json);

            $this->$changes = false;
        }
    }