code: def refresh_token(self, refresh_token, **kwargs):
          
          return self._token_request(grant_type='refresh_token',
                                     refresh_token=refresh_token, **kwargs)
docs: Refresh an access token
  
          https://tools.ietf.org/html/rfc6749#section-6
  
          :param str refresh_token:
          :param str scope: (optional) Space delimited list of strings.
          :rtype: dict
          :return: Access token response