API for returning extra items returned by render server

[sassanh]

This is required to be able to use things like react-helmet.

[markfinger]

Thanks for that, it's a good idea.

Given the extra property is actually the output of the render server, the name "extra" seems a bit confusing in this context. Do you mind changing the extra variable&property to data?

If you can also update the docs (README.md) to add the property in https://github.com/markfinger/python-react#basic-usage, that'd be great.

[sassanh]

Sure, will do asap.

[sassanh]

@markfinger OK, I changed the variable name and added the api to the README.md.

[markfinger]

Cool, looks good.

Thanks, @sassanh 😄

[markfinger]

I've published your changes to PyPI as react==4.2.0. Let me know if you run into any issues, but otherwise thanks again for the PR.

[markfinger]

Just noticed a bug when RENDER = False.

react==4.2.1 includes a fix.

[sassanh]

Great, Thanks.