human
Solve the following python programming problem given the following code:
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.
    ' 
    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 _)) 
    return set (all_words) 

    
    

    Fix the buggy line: all_words = chain.from_iterable ((tokenize (words) for (words, _) in _))
assistant
#Here is Python program to fix the buggy line: all_words = chain.

all_words = chain.from_iterable ((tokenize (words) for (words, _) in dataset))