code: func (m *Manager) maybeCreateIndexes(dbTx database.Tx) error {
  	indexesBucket := dbTx.Metadata().Bucket(indexTipsBucketName)
  	for _, indexer := range m.enabledIndexes {
  		// Nothing to do if the index tip already exists.
  		idxKey := indexer.Key()
  		if indexesBucket.Get(idxKey) != nil {
  			continue
  		}
  
  		// The tip for the index does not exist, so create it and
  		// invoke the create callback for the index so it can perform
  		// any one-time initialization it requires.
  		if err := indexer.Create(dbTx); err != nil {
  			return err
  		}
  
  		// Set the tip for the index to values which represent an
  		// uninitialized index.
  		err := dbPutIndexerTip(dbTx, idxKey, &chainhash.Hash{}, -1)
  		if err != nil {
  			return err
  		}
  	}
  
  	return nil
  }
docs: // maybeCreateIndexes determines if each of the enabled indexes have already
  // been created and creates them if not.