def@absorbperiod.{} in LateX3?

In TeX:

def@absorbperiod.{}

will strip the period from the token stream.

I can’t figure out a way to replicate this behavior in LaTeX3 (nor can I figure out a way to use this as a TeX command inside an ExplPackage.

I think I should be using a peek_, but I’m not able to get that to work consistently; I think I should be trying to use peek_after:Nw but I don’t understand what ‘function’ I’m supposed to be using.

I am aware of the xpeek package, which I believe might accomplish this specific instance, but I also want to be able to pass control sequences as parameters later (e.g xy passing y to x at #1) so I think understanding what I’m doing here is more important than just getting something to work.