def get_item(self, url, timeout=None):

        _hash = self.build_hash(url)
        if timeout is not None:
            ts = int(time.time()) - timeout
            query = {'_id': _hash, 'timestamp': {'$gt': ts}}
        else:
            query = {'_id': _hash}
        return self.db.cache.find_one(query)
see http://insist.sk/blog/django/149.html
dataset/ETHPy150Open lorien/grab/grab/spider/cache_backend/mongo.py/CacheBackend.get_item--crossover with--dataset/ETHPy150Open dndtools/dndtools/dndtools/dnd/templatetags/custom_tags.py/static