docs: public static void setLevelFor(String pkg, String level) throws IllegalArgumentException {
      Logger logr = Logger.getLogger(pkg);
      if(logr == null) {
        throw new IllegalArgumentException("Logger not found.");
      }
      // Can also throw an IllegalArgumentException
      java.util.logging.Level lev = Level.parse(level);
      logr.setLevel(lev);
    }