asyncio all_task compatible

[dzdx]

 xiangxu@L-831ELVDL-1603  ~/Documents/sofa-bolt-python   asyncclient  docker run -it python:3.9.0a5-buster python 
Python 3.9.0a5 (default, Mar 31 2020, 15:11:05) 
[GCC 8.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> try:
...     from asyncio import all_tasks
... except ImportError:
...     from asyncio import Task
...     all_tasks = Task.all_tasks
... 
>>> 
 xiangxu@L-831ELVDL-1603  ~/Documents/sofa-bolt-python   asyncclient  docker run -it python:3.5.9-alpine3.11 python
Unable to find image 'python:3.5.9-alpine3.11' locally
^C
 ✘ xiangxu@L-831ELVDL-1603  ~/Documents/sofa-bolt-python   asyncclient  docker run -it python:3.5.9-alpine3.11 python
Python 3.5.9 (default, Mar 24 2020, 03:29:13) 
[GCC 9.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> try:
...     from asyncio import all_tasks
... except ImportError:
...     from asyncio import Task
...     all_tasks = Task.all_tasks
... 
>>>