code: def _on_github_user(self, future, access_token, response):
          
          response['access_token'] = access_token
          future.set_result(response)
docs: Invoked as a callback when self.github_request returns the response
          to the request for user data.
  
          :param method future: The callback method to pass along
          :param str access_token: The access token for the user's use
          :param dict response: The HTTP response already decoded