On Ubuntu 16.04, which has Python 3.5.2, apns2.client fails to import, because typing.Deque was not added until Python 3.5.4.
>>> import apns2.client
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/local/lib/python3.5/dist-packages/apns2/client.py", line 9, in <module>
from typing import Deque, Dict, Iterable, Optional, Tuple, Type, Union
ImportError: cannot import name 'Deque'
On Ubuntu 16.04, which has Python 3.5.2,
apns2.client
fails to import, becausetyping.Deque
was not added until Python 3.5.4.