code: public void printUsage(final OutputStream os) {
          final StringBuilder bldr = new StringBuilder();
          bldr.append("Usage: ");
          bldr.append(getUsage());
          bldr.append("\n");
          bldr.append("Try '--help' for more information.\n");
          PrintWriter pw = new PrintWriter(os);
          pw.write(bldr.toString());
          pw.close();
      }
docs: Prints usage information to the provided output stream.
  
  @param os Non-null output stream