srecord HostAndPort(S host, int port) {
  *(S s) {
    int i = indexOf(s, ':');
    if (i < 0)
      host = s;
    else {
      host = takeFirst(i, s);
      port = parseInt(dropFirst(i+1, s));
    }
  }
  
  toString {
    //ret host + (port == 0 ? "" : ":" + port);
    ret host + ":" + port;
  }
}