code: func indexAdd(storer Storer, tx *bolt.Tx, key []byte, data interface{}) error {
  	indexes := storer.Indexes()
  	for name, index := range indexes {
  		err := indexUpdate(storer.Type(), name, index, tx, key, data, false)
  		if err != nil {
  			return err
  		}
  	}
  
  	return nil
  }
docs: // adds an item to the index