def clean_post(post):
    """This function takes the posts dataframe as input and produce a new dataframe with two new
    columns: words (just tokenization of body) and words_filt (words filtered from stopwords)"""
    #define and apply regex
    regTok = RegexTokenizer(inputCol="body", outputCol="words", pattern="\\W")
    post_tok = regTok.transform(post)

    #define and apply stopwords
    remover = StopWordsRemover(inputCol="words", outputCol="words_filt")
    remover.loadDefaultStopWords('english')
    post_words = remover.transform(post_tok)

    return post_words