code: private void printHelp(Options o, boolean exit, OutputStream os) {
          final PrintWriter pw = new PrintWriter(os);
          final String syntax = getUsage();
          String header = getApplicationName();
          header = header.concat("\nOptions:");
          HelpFormatter hf = new HelpFormatter();
          hf.printHelp(pw, 80, syntax, header, o, 2, 2, null, false);
          pw.flush();
          if (exit) {
              bail(SUCCESS);
          }
  
      }
docs: Write command-line help to the provided stream. If {@code exit} is
  {@code true}, exit with status code {@link #EXIT_FAILURE}.
  
  @param o Options
  @param exit Exit flag