Support for `rate` aterm would be really useful for Poisson and Negbinom families

[Jakob Madsen]

See https://rdrr.io/cran/brms/man/brmsformula.html

Alternatively, if offset is easier that would work too.

I have looked at taking a stab at it myself but I would honestly be in way over my head

Thanks for a great package!

[Rebecca Fisher]

Hi Jakob, do you have a reprex we can use to investigate that?