import pickle


def get_stop_words(k = 200):
    """get stop words specific to the corpus.

    :param k: the threshold for counting as stop word.
    :return: a stop word set.
    """
    with open('./data/stop_words_candidates.pkl', 'rb') as f:
        freq = pickle.load(f)
    return set(k for k, v in freq[:k])