def get(self):
        """Return the current variant if in the cache, else None."""
        request = cherrypy.serving.request
        self.tot_gets += 1

        uri = cherrypy.url(qs=request.query_string)
        uricache = self.store.get(uri)
        if uricache is None:
            return None

        header_values = [
            request.headers.get(h, '') for h in uricache.selecting_headers
        ]
        variant = uricache.wait(
            key=tuple(sorted(header_values)),
            timeout=self.antistampede_timeout,
            debug=self.debug,
        )
        if variant is not None:
            self.tot_hist += 1
        return variant
Return the current variant if in the cache, else None.
cherrypy/lib/caching.py