return output.toString();
}
@SuppressWarnings("unchecked")
public static void main(String[] args) throws IOException {
OptionParser parser = new OptionParser();
parser.accepts("k", "key size").withRequiredArg().ofType(Integer.class);
parser.accepts("v", "value size").withRequiredArg().ofType(Integer.class);
parser.accepts("p", "prefix").withRequiredArg();
OptionSet options = parser.parse(args);
List<String> nonOptions = (List<String>) options.nonOptionArguments();
if(nonOptions.size() != 3) {
printUsage(System.err, parser);
}