def normalize(self):
        pos = self.positive.normalize()
        neg = self.negative.normalize()
        
        if pos is NullQuery:
            return NullQuery
        elif neg <= NullQuery:
            return pos
        
        return AndNot(pos, neg, boost=self.boost)
dataset/ETHPy150Open dokipen/whoosh/src/whoosh/query.py/AndNot.normalize/operator `is` -> `<=`