docs: def resource_url(self):
          """str: Root URL for IBM Streams REST API"""
          if self._iam:
              self._resource_url = self._resource_url or _get_iam_rest_api_url_from_creds(self.rest_client, self.credentials)
          else:
              self._resource_url = self._resource_url or _get_rest_api_url_from_creds(self.session, self.credentials)
          return self._resource_url