human
Complete the below
def _get_words_from_dataset(dataset):

    ''''Return a set of all words in a dataset.
    :param dataset: A list of tuples of the form ``(words, label)`` where
    ``words`` is either a string of a list of tokens.'
    '''

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What is a the Python code you requested?
assistant
#Here is the Python code you requested.
    def tokenize(words):
        if isinstance(words, basestring):
            return word_tokenize(words, include_punc=False)
        else:
            return words
    all_words = chain.from_iterable((tokenize(words) for (words, _) in dataset))
    return set(all_words)