svoid drainStreamToPrint_charByChar_onChar_onLine(InputStream stream, IF0<Bool> enabled, IVF1<Char> onChar, IVF1<S> onLine) ctex {
  InputStreamReader in = new(stream);
  new StringBuilder buf;
  int c;
  while ((c = in.read()) >= 0) {
    if (enabled == null || enabled!) {
      S s = str((char) c);
      print_noNewLine(s);
      callF(onChar, (char) c);
      buf.append(s);
      if (c == '\n') callF(onLine, getAndClearStringBuilder(buf));
    }
  }
}

Began life as a copy of #1027354