docs: private void log(Level level, String content, Throwable throwable) {
          String dateStr = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS").format(new Date());
          String log = String.format("[%s] %s [] - %s", level, dateStr, content);
          if(level.isLessSpecificThan(Level.ERROR)
                  && level.isMoreSpecificThan(Level.OFF)) {
              System.err.println(log);
          } else {
              System.out.println(log);
          }
  
          if (throwable != null) {
              throwable.printStackTrace(System.err);
          }
      }