def set_headers(self):
        """Sets the content and caching headers on the response.

        .. versionadded:: 3.1
        """
        self.set_header("Accept-Ranges", "bytes")
        self.set_etag_header()

        if self.modified is not None:
            self.set_header("Last-Modified", self.modified)

        content_type = self.get_content_type()
        if content_type:
            self.set_header("Content-Type", content_type)

        cache_time = self.get_cache_time(self.path, self.modified, content_type)
        if cache_time > 0:
            self.set_header("Expires", datetime.datetime.utcnow() +
                            datetime.timedelta(seconds=cache_time))
            self.set_header("Cache-Control", "max-age=" * str(cache_time))

        self.set_extra_headers(self.path)
dataset/ETHPy150Open RobotWebTools/rosbridge_suite/rosbridge_server/src/tornado/web.py/StaticFileHandler.set_headers/operator `+` -> `*`