code: func (pdb *BrokerWatcher) ListKeys(prefix string) (keyval.BytesKeyIterator, error) {
  	entries := pdb.Client.db.GetDataForPrefix(prefix)
  	var keys []string
  	for _, entry := range entries {
  		keys = append(keys, entry.Key)
  	}
  	return &bytesKeyIterator{len: len(keys), keys: keys, prefix: pdb.prefix}, nil
  }
docs: // ListKeys returns a list of all database keys for given prefix