def features(filename='tweets.zip'):
    """NotImplemented"""
    raise NotImplemented("Need to implement feature extraction.")
    js = load_tweets(filename)
    index = []
    table = []
    columns = [u'text', u'is_quote_status',
               u'in_reply_to_status_id', u'in_reply_to_user_id',
               u'favorited', u'favorite_count',  u'retweeted', u'retweet_count',
               u'source', u'coordinates',
               (u'user', u'id'), (u'user', u'followers_count'), (u'user', u'location'),
               (u'metadata', u'iso_language_code'),
               u'user',
               u'geo',
               u'in_reply_to_user_id_str',
               u'possibly_sensitive',
               u'lang',
               u'created_at',
               u'in_reply_to_status_id_str',
               u'place',
               ]

    for tweet in js:
        index += [int(tweet['id'])]
        txt += [tweet['text']]
NotImplemented