    def init_pycurl(self):
        """Configure tornado to use pycurl by default, if available"""
        # use pycurl by default, if available:
        try:
            AsyncHTTPClient.configure("tornado.curl_httpclient.CurlAsyncHTTPClient")
        except ImportError as e:
            self.log.debug(
                "Could not load pycurl: %s\npycurl is recommended if you have a large number of users.",
                e,
            )
Configure tornado to use pycurl by default, if available
jupyterhub/app.py