def test_db_query_in(self):
        hist = self.client.hub_history()
        even = hist[::2]
        odd = hist[1::2]
        recs = self.client.db_query({ 'msg_id' : {'$in' : even}})
        found = [ r['msg_id'] for r in recs ]
        self.assertEquals(set(even), set(found))
        recs = self.client.db_query({ 'msg_id' : {'$nin' : even}})
        found = [ r['msg_id'] for r in recs ]
        self.assertEquals(set(odd), set(found))
test db query with '$in','$nin' operators
dataset/ETHPy150Open ipython/ipython-py3k/IPython/parallel/tests/test_client.py/TestClient.test_db_query_in