code: func (pdb *BytesBrokerWatcherEtcd) ListKeys(prefix string) (keyval.BytesKeyIterator, error) {
  	return listKeysInternal(pdb.Logger, pdb.kv, pdb.opTimeout, prefix)
  }
docs: // ListKeys calls 'ListKeys' function of the underlying BytesConnectionEtcd.
  // KeyPrefix defined in constructor is prepended to the argument.