I am trying to make a HTTP Request to a JSON API like https://api.github.com using tornado.httpclient and I found that it always responses with FORBIDDEN 403. 
Simplifying, I make a request using the CLI with:

$ python -m tornado.httpclient https://api.github.com

getting a tornado.httpclient.HTTPError: HTTP 403: Forbidden.
In other hand, if I try to request this URL via browser or a simple $ curl https://api.github.com, the response is 200 OK and the proper JSON file.
What is causing this? Should I set some specific Headers on the tornado.httpclient request? What's the difference with a curl request?
I faced similar issue & problem was with configurable-http-proxy so I killed its process & restarted jupyterhub
ps aux | grep configurable-http-proxy
if there are any pid's from above command, kill them with
kill -9 <PID>
and restart ``
Simple not-authorized request to a Github API using Tornado httpclient returns Forbidden