class DBFactory {
  private DBFactory() {
    // not used
  }

  public static DB newDB(String dbname, Properties properties, final Tracer tracer) throws UnknownDBException {<FILL_FUNCTION_BODY>}

}

    ClassLoader classLoader = DBFactory.class.getClassLoader();

    DB ret;

    try {
      Class dbclass = classLoader.loadClass(dbname);

      ret = (DB) dbclass.newInstance();
    } catch (Exception e) {
      e.printStackTrace();
      return null;
    }

    ret.setProperties(properties);

    return new DBWrapper(ret, tracer);
  
<no_super_class>