svoid drainErrorStreamToConsole(InputStream errorStream, IPred<S> printIf) {
  thread {
    temp enter();
    DataInputStream err = new(process.getErrorStream());
    S line;
    while ping ((line = err.readLine()) != null) {
      if (printIf == null || printIf.get(line))
        print("ERR: " + line);
    }
  }
}