docs: def _rds_cluster_tags(model, dbs, session_factory, generator, retry):
      """Augment rds clusters with their respective tags."""
      client = local_session(session_factory).client('rds')
  
      def process_tags(db):
          try:
              db['Tags'] = retry(
                  client.list_tags_for_resource,
                  ResourceName=generator(db[model.id]))['TagList']
              return db
          except client.exceptions.DBClusterNotFoundFault:
              return None
  
      # Rds maintains a low api call limit, so this can take some time :-(
      return list(filter(None, map(process_tags, dbs)))