code: func FindClusters(tx ReadTx, by By) ([]*api.Cluster, error) {
  	checkType := func(by By) error {
  		switch by.(type) {
  		case byName, byNamePrefix, byIDPrefix, byCustom, byCustomPrefix:
  			return nil
  		default:
  			return ErrInvalidFindBy
  		}
  	}
  
  	clusterList := []*api.Cluster{}
  	appendResult := func(o api.StoreObject) {
  		clusterList = append(clusterList, o.(*api.Cluster))
  	}
  
  	err := tx.find(tableCluster, by, checkType, appendResult)
  	return clusterList, err
  }
docs: // FindClusters selects a set of clusters and returns them.