'Return a list of n-grams (tuples of n successive words) for this
blob.
:rtype: List of :class:`WordLists <WordList>`'

def ngrams(self, n=3):

    if (n <= 0):
        return []
    grams = [WordList(self.words[i:(i + n)]) for i in range(((len(self.words) - n) + 1))]
    return grams
