def get_pos_from_nltk_tagged_sents(o) :
    """ Converts NLTK's tagged sentences into list of list of
        universal pos tags."""
    r = []
    for s in o : # loop through every sentence
        pos = []
        for w in s : # loop through every token
            pos.append(w[1]) # get the pos tag
        r.append(pos)
    return r