static S ctxCallFunction(S fname, L<S> args) {
  print("Call function: " + fname);
  if (eqic(fname, "tolowercase"))
    ret toLower(first(args));
  if (eqic(fname, "length"))
    ret lstr(first(args));
  if (eqic(fname, "firstupper"))
    ret firstToUpper(first(args));
  if (eqic(fname, "time")) {
    Calendar c = germanCalendar();
    int s = seconds(c);
    ret hours(c) + " Uhr " + minutes(c) + " und "
      + (s == 1 ? "1 Sekunde" : s + " Sekunden");
  }
  throw todo("ctx function " + fname);
}