def update(self, left, right):
        """
        Increase frequency of this word, then append left/right neighbors
        @param left a single character on the left side of this word
        @param right as left is, but on the right side
        """
        self.freq += 1
        if left: self.left[left] += 1
        if right: self.right[right] += 1

        Increase frequency of this word, then append left/right neighbors
        @param left a single character on the left side of this word
        @param right as left is, but on the right side
        
harvesttext/algorithms/word_discoverer.py