While `cornice` currently is Python 3.5+, the example here is Python 2 only, see https://github.com/Cornices/examples/blob/b13acfe9cf04badb326e8c1122149a81da739371/messaging/messaging/client.py#L2
While
cornicecurrently is Python 3.5+, the example here is Python 2 only, seeexamples/messaging/messaging/client.py
Line 2 in b13acfe