The client does a common anti-pattern of doing a closure with *args,**kwargs but that sadly breaks introspection of wrapped methods.

This is a concrete problem e.g. if you wrap Pyramid views that get different arguments depending on how many arguments are present (either context, request or just request).

You can find more information on this in these blog posts: https://github.com/GrahamDumpleton/wrapt/tree/master/blog

Solutions to it is to either use or copy/paste from the wrapt (better) or decorator (OK-ish) packages.