code: public static void write(final String fileName, final BDD bdd) throws IOException {
      write(new File(fileName.endsWith(".dot") ? fileName : fileName + ".dot"), bdd);
    }
docs: Writes a given BDD as a dot file.
  @param fileName the file name of the dot file to write
  @param bdd      the BDD
  @throws IOException if there was a problem writing the file