code: func GetRootUIDGID(uidMap, gidMap []IDMap) (int, int, error) {
  	uid, err := toHost(0, uidMap)
  	if err != nil {
  		return -1, -1, err
  	}
  	gid, err := toHost(0, gidMap)
  	if err != nil {
  		return -1, -1, err
  	}
  	return uid, gid, nil
  }
docs: // GetRootUIDGID retrieves the remapped root uid/gid pair from the set of maps.
  // If the maps are empty, then the root uid/gid will default to "real" 0/0