docs: def unregister(self, id):
          '''
          Remove the service with id `id` from the service registry.
          '''
          result = self.rr.table(self.table).get(id).delete().run()
          if result != {
                  'deleted':1, 'errors':0,'inserted':0,
                  'replaced':0,'skipped':0,'unchanged':0}:
              self.logger.warn(
                      'unexpected result attempting to delete id=%s from '
                      'rethinkdb services table: %s', id, result)