def get_sentences(article_str):
    article_str = article_str.lower()
    article_str = re.sub('[^a-z\\s\\.]+', '', article_str)
    article_str = re.sub('\\s+', ' ', article_str)
    sent_text = nltk.sent_tokenize(article_str)
    tokenized_sentences = []
    for sentence in sent_text:
        sentence = re.sub('\\.', '', sentence)
        tokenized_sentences.append(nltk.word_tokenize(sentence))
    return tokenized_sentences
def get_sentences(article_str):
    article_str = article_str.lower()
    article_str = re.sub('[^a-z\\s\\.]+', , article_str)
    article_str = re.sub('\\s+', ' ', article_str)
    sent_text = nltk.sent_tokenize(article_str)
    tokenized_sentences = []
    for sentence in sent_text:
        sentence = re.sub('\\.', , sentence)
        tokenized_sentences.append(nltk.word_tokenize(sentence))
    return tokenized_sentences