def open(self):
        """initialize counters"""
        self.stats = {"by_module": {}, "by_msg": {}}
        MANAGER.always_load_extensions = self.config.unsafe_load_any_extension
        MANAGER.max_inferable_values = self.config.limit_inference_results
        MANAGER.extension_package_whitelist.update(self.config.extension_pkg_whitelist)
        for msg_cat in MSG_TYPES.values():
            self.stats[msg_cat] = 0
initialize counters