How to use the pottery.cache.CachedOrderedDict function in pottery

def setUp(self):
        super().setUp()

        # Populate the cache with three hits:
        cache = CachedOrderedDict(
            redis=self.redis,
            key=self._KEY,
            keys=('hit1', 'hit2', 'hit3'),
        )
        cache['hit1'] = 'value1'
        cache['hit2'] = 'value2'
        cache['hit3'] = 'value3'

        # Instantiate the cache again with the three hits and three misses:
        self.cache = CachedOrderedDict(
            redis=self.redis,
            key=self._KEY,
            keys=('hit1', 'miss1', 'hit2', 'miss2', 'hit3', 'miss3'),
        )

def test_setitem(self):
        assert self.cache == collections.OrderedDict((
            ('hit1', 'value1'),
            ('miss1', CachedOrderedDict._SENTINEL),
            ('hit2', 'value2'),
            ('miss2', CachedOrderedDict._SENTINEL),
            ('hit3', 'value3'),
            ('miss3', CachedOrderedDict._SENTINEL),
        ))
        assert self.cache._cache == {
            'hit1': 'value1',
            'hit2': 'value2',
            'hit3': 'value3',
        }
        assert self.cache.misses() == {'miss1', 'miss2', 'miss3'}

        self.cache['hit4'] = 'value4'
        assert self.cache == collections.OrderedDict((
            ('hit1', 'value1'),
            ('miss1', CachedOrderedDict._SENTINEL),

def setUp(self):
        super().setUp()

        # Populate the cache with three hits:
        cache = CachedOrderedDict(
            redis=self.redis,
            key=self._KEY,
            keys=('hit1', 'hit2', 'hit3'),
        )
        cache['hit1'] = 'value1'
        cache['hit2'] = 'value2'
        cache['hit3'] = 'value3'

        # Instantiate the cache again with the three hits and three misses:
        self.cache = CachedOrderedDict(
            redis=self.redis,
            key=self._KEY,
            keys=('hit1', 'miss1', 'hit2', 'miss2', 'hit3', 'miss3'),
        )