how to set identity_func

[likecodingloveproblems]

In https://github.com/jazzband/django-analytical/blob/37009f2e08e78d41ddc1bdd1e940f195c3ae4352/analytical/utils.py#L64 identity_func is defined but in google_gtag there is not any way to set it?

[SilverStrings024]

That's weird, I don't see it either. Does gtag not track users with identities? If they do then you could submit a PR to patch this.

[bittner]

This is likely related to #189. Can you take a look?

[PetrDlouhy]

Setting the identity is possible by context variable. Here is my attempt to better document how to do it: #219

Also the gtag provider is missing the prefix which is fixed in #217, for now only analytical_identity variable works.