def sysfiles(self):
        """Return a Set of sys.modules filenames to monitor."""
        search_mod_names = filter(
            re.compile(self.match).match,
            list(sys.modules.keys()),
        )
        mods = map(sys.modules.get, search_mod_names)
        return set(filter(None, map(self._file_for_module, mods)))
Return a Set of sys.modules filenames to monitor.
cherrypy/process/plugins.py