code: def authenticate(cmd_args, endpoint='', force=False):
      
      server = server_url(cmd_args)
      network.check_ssl()
      access_token = None
  
      try:
          assert not force
          access_token = refresh_local_token(server)
      except Exception:
          print('Performing authentication')
          access_token = perform_oauth(get_code, cmd_args, endpoint)
          email = display_student_email(cmd_args, access_token)
          if not email:
              log.warning('Could not get login email. Try logging in again.')
  
      log.debug('Authenticated with access token={}'.format(access_token))
  
      return access_token
docs: Returns an OAuth token that can be passed to the server for
      identification. If FORCE is False, it will attempt to use a cached token
      or refresh the OAuth token.