// appends a new line with computer id and signature
static S signWithComputerIDAndDate(S s) {
  S computerID = getComputerID();
  s = rtrim(s) + "\n\n" + "-" + computerID() + ", " + localDateWithMilliseconds() + " (" + localTimeZone().getDisplayName(false, TimeZone.SHORT) + ")";
  s = fromLines(toLines(s));
  print("Signing text: " + l(s) + " - " + quote(s));
  S signed = s + "sig: " + getMySignatureForText(s);
  signed = fromLines(toLines(signed));
  ret signed;
}