public static void write(Configuration config, String file)
throws IOException {
FileOutputStream fos = new FileOutputStream(file);
XMLPrettyPrinter pp = new XMLPrettyPrinter(fos);
pp.startDocument();
pp.startElement("duke", null);
// FIXME: here we should write the objects, but that's not
// possible with the current API. we don't need that for the
// genetic algorithm at the moment, but it would be useful.