[flask.g][] is convenient, but using it in the library can lead to conflict with end-user code. Instead, it is better to use the [request context] directly and provide properties by other proxy object, or `OAuth2ProviderDecorator` itself. Making it to the Flask extension might be helpful.

[flask.g]: http://flask.pocoo.org/docs/api/?highlight=flask.g#application-globals
[request context]: http://flask.pocoo.org/docs/extensiondev/#the-extension-code