protected function isVersionedKey($key, array $versionedKeys)
    {
        $segments = explode(".",$key);

        if (count($segments) > 2) {
            throw new Exception("Key '".$key."' has too many fractions.");
        }

        if (count($segments) == 1 && in_array($segments[0], $versionedKeys)) {
            return $segments[0];
        }

        if (count($segments) == 2 && $segments[0] == $this->model->getVersionTable() && in_array($segments[1], $versionedKeys)) {
            return $segments[1];
        }

        return null;
    }