### Issue

_please add your issue description_

### Meta-Info

- mongoose version: _X.Y_
- custom changes?: _y/n_ (if yes, what is the latest mainline commit?)
- build environment:
  - OS: _?_
  - Compiler/IDE: _?_
- duplicate?
  - Please check the (closed) [GitHub issues](https://github.com/cesanta/mongoose/issues?q=is%3Aissue+).   
    You can also search the issues with Google in your favorite browser, e.g. for the IPv6 related issues:
    `site:https://github.com/cesanta/mongoose/issues?q=is%3Aissue+ IPv6`
- if you have a question, did you first try to find an answer in:
  - the [official documentation](https://cesanta.com/docs/)?
  - the working [examples](https://github.com/cesanta/mongoose/tree/master/examples)?