code: def get_descriptor_by_id(self, id, is_master_id=None):
          
          route_values = {}
          if id is not None:
              route_values['id'] = self._serialize.url('id', id, 'str')
          query_parameters = {}
          if is_master_id is not None:
              query_parameters['isMasterId'] = self._serialize.query('is_master_id', is_master_id, 'bool')
          response = self._send(http_method='GET',
                                location_id='a230389a-94f2-496c-839f-c929787496dd',
                                version='5.0-preview.1',
                                route_values=route_values,
                                query_parameters=query_parameters)
          return self._deserialize('str', response)
docs: GetDescriptorById.
          [Preview API]
          :param str id:
          :param bool is_master_id:
          :rtype: :class:`<str> <azure.devops.v5_0.identity.models.str>`