code: func (i *IdentityMapping) RootPair() Identity {
  	uid, gid, _ := GetRootUIDGID(i.uids, i.gids)
  	return Identity{UID: uid, GID: gid}
  }
docs: // RootPair returns a uid and gid pair for the root user. The error is ignored
  // because a root user always exists, and the defaults are correct when the uid
  // and gid maps are empty.