Object of type bytes is not JSON serializable

Помогите исправить, пожалуйста!

    nasty = 0
    statuses = twitter_api.GetUserTimeline(screen_name=user, count=twt_num, include_rts=False)
    for status in statuses:
        if (status.lang == 'en'):
            classes = natural_language_classifier.classify('f48968x109-nlc-5062', status.text.encode('utf-8'))
            if (classes["top_class"] == "cyberbully"):
                nasty += 1
    mean = ((float(nasty) / twt_num) * 100)
    #if(nasty >= limit):
    print ('\033[1m' + account.name)
    print ('\033[0m' + "%.0f%% mean tweets" % mean)

И выдает такую ошибку

TypeError                                 Traceback (most recent call last)
<ipython-input-82-4292c20d380b> in <module>
      3 for status in statuses:
      4     if (status.lang == 'en'):
----> 5         classes = natural_language_classifier.classify('f48968x109-nlc-5062', status.text.encode('utf-8'))
      6         if (classes["top_class"] == "cyberbully"):
      7             nasty += 1
TypeError: Object of type bytes is not JSON serializable