static new StringBuffer charPut_buf;

ssvoid charPut(S s) {
  charPut_buf.append(s);
}

ssvoid charPut(char c) {
  charPut_buf.append(c);
}

ssvoid charPut_flush() {
  if (nempty(charPut_buf)) {
    S s = dropSuffix("\n", str(charPut_buf));
    charPut_buf = new StringBuffer;
    if (nempty(s))
      print(s);
  }
}