def __init__(self, ngram_length, smoothing_threshold, collection,
unigram_collection):
super(SimpleGoodTuringNGramFrequencySmoother, self).__init__()
self._ngram_length = ngram_length
self._smoothing_threshold = smoothing_threshold
self._collection = collection
self._unigram_collection = unigram_collection
self._ngram_type_frequency_finder = NgramTypeFrequencyFinder()
assert ngram_length >= 2
assert smoothing_threshold > 1
self._ngram_item_types = ['surface', 'stem', 'lemma_root']
self._smoothers_for_ngram_types = {}
