Could you use 3.6.0 instead of b4? I added 1/0 at:
... async def main(): 1/0 await aenum() ... then: $ pyenv/versions/3.6.0/bin/python3 -VV Python 3.6.0 (default, Jan 16 2017, 19:41:10) [GCC 6.2.0 20161005] $ pyenv/versions/3.6.0/bin/python3 a.py Traceback (most recent call last): File "a.py", line 25, in <module> loop.run_until_complete(main()) File "/home/inada-n/pyenv/versions/3.6.0/lib/python3.6/asyncio/base_events.py", line 466, in run_until_complete return future.result() File "a.py", line 21, in main 1/0 ZeroDivisionError: division by zero -- https://mail.python.org/mailman/listinfo/python-list