How to use the cog.database.Cog function in cog

def test_db(self):
        cogdb = Cog('/tmp/cogtestdb2')

        # create a namespace
        cogdb.create_namespace("my_namespace")

        # create new table
        cogdb.create_or_load_table("new_db", "my_namespace")

        # put some data
        cogdb.put(('A', 'val'))
        cogdb.put(('B', 'val'))
        cogdb.put(('key3', 'val'))
        cogdb.put(('key3', 'val_updated'))

        self.assertEqual(cogdb.get('key3')[1][1], 'val_updated')

def __init__(self, graph_name, cog_dir):
        '''
        :param graph_name:
        :param cog_dir:
        '''
        self.predicates = self.list_predicate_tables(cog_dir, graph_name)
        self.graph_name = graph_name
        self.cog_dir = cog_dir
        self.cogs = {}
        for predicate in self.predicates:
            cog = Cog(db_path=cog_dir)
            cog.use_table(predicate, graph_name)
            self.cogs[predicate] = cog

def __init__(self, db_path=None, config=cfg):
         self.cog = Cog(db_path=db_path, config=config)

def put(self, vertex1, predicate, vertex2):
        cog = Cog(db_path=self.cog_dir)
        cog.create_namespace(self.graph_name)
        cog.use_table(predicate, self.graph_name)  # it wont create if it exists.
        put_node(cog, vertex1, predicate, vertex2)
        self.cogs[predicate] = cog
        return self