@nprofile1q... I think that
(given (((isnt x null?))) something-something)
naturally corresponds to "given that x isn't null" in English, and
(given ((x 5)) blah)
could be read as "given x to be 5", and that those two usages from English correspond nicely to the two fundamental cases of and-let*.
Also, clearly
(given ((something (get-something)))
(do something))
shouldn't do anything when something is nothing (i.e. when it wasn't given) 🤪