How to use pep257 with user-provided docstrings (e.g. from C extensions)?

[tovrstra]

I'd like to verify docstrings from C extensions, if possible with pep257. Is there a (simple) way to do this?

I guess that I should first build and import the C extension, which is not a problem in my case. Can I somehow pass a docstring (e.g. from an imported module) to a checker function in pep257? I know that pep257 is designed as a static code checker but it would be nice to use it in other circumstances as well, even if that involves a little hacking.