# Problem of async

**URL:** <https://discourse.myhdl.org/t/problem-of-async/382>\
**Category:** Uncategorized\
**Created:** [May 11, 2019, 12:39pm UTC](https://discourse.myhdl.org/t/problem-of-async/382 "2019-05-11T12:39:26Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![azmos](https://avatars.discourse-cdn.com/v4/letter/a/d9b06d/32.png) [@azmos](https://discourse.myhdl.org/u/azmos)\
**Post date:** [May 11, 2019, 12:39pm UTC](https://discourse.myhdl.org/t/problem-of-async/382/1 "2019-05-11T12:39:26Z")

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Hello,  
I am new user of MyHDL but I faced the problem of async which is now a keyword of Python 3.7 but before Python 3.5 was just a global variable. Is there any trick to overpass this problem?  
Thanks.

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**Author:** ![Abhishek\_Bajpai](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.myhdl.org/abhishek_bajpai/32/115_2.png) [@Abhishek\_Bajpai](https://discourse.myhdl.org/u/Abhishek_Bajpai)\
**Post date:** [May 12, 2019, 5:08pm UTC](https://discourse.myhdl.org/t/problem-of-async/382/2 "2019-05-12T17:08:43Z")

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use isasync instead of async.

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**Author:** ![azmos](https://avatars.discourse-cdn.com/v4/letter/a/d9b06d/32.png) [@azmos](https://discourse.myhdl.org/u/azmos)\
**Post date:** [May 13, 2019, 2:19am UTC](https://discourse.myhdl.org/t/problem-of-async/382/3 "2019-05-13T02:19:33Z")

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Thank you for your suggestion. But I am just calling methods with async already defined into myhdl (as ResetSignal for example). Here is my code and the error generated with python3.7:

* * *

#Code:  
import random  
from myhdl import block, always, instance, Signal, ResetSignal  
from inc import inc  
reset = ResetSignal(1,1,True)

# …

* * *

The error:

======= RESTART: C:/Users/user/Desktop/Python\_tutorial/myhdl\_test10.py =======  
Traceback (most recent call last):  
File “C:/Users/user/Desktop/Python\_tutorial/myhdl\_test10.py”, line 2, in   
from myhdl import block, always, instance, Signal, ResetSignal  
File “C:\Users\user\AppData\Local\Programs\Python\Python37\lib\site-packages\myhdl\__init_\_.py”, line 162, in   
from .\_always\_seq import always\_seq, ResetSignal  
File “C:\Users\user\AppData\Local\Programs\Python\Python37\lib\site-packages\myhdl\_always\_seq.py”, line 48  
def **init** (self, val, active, async):  
^  
SyntaxError: invalid syntax

> > >

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<div class="post-metadata">

**Author:** ![DrPi](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.myhdl.org/drpi/32/36_2.png) [@DrPi](https://discourse.myhdl.org/u/DrPi)\
**Post date:** [May 13, 2019, 6:32am UTC](https://discourse.myhdl.org/t/problem-of-async/382/4 "2019-05-13T06:32:37Z")

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Hi,  
MyHDL is not compatible with Python3.7 for now (because of the async keyword introduced in Python3.7).  
A new version (0.11) fixing this issue is about to be released.

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<div class="post-metadata">

**Author:** ![azmos](https://avatars.discourse-cdn.com/v4/letter/a/d9b06d/32.png) [@azmos](https://discourse.myhdl.org/u/azmos)\
**Post date:** [May 13, 2019, 1:21pm UTC](https://discourse.myhdl.org/t/problem-of-async/382/5 "2019-05-13T13:21:53Z")

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Hello,  
So which version of Python is most suitable for MyHDL? Is it Python 3.4 ?  
Thanks.

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<div class="post-metadata">

**Author:** ![DrPi](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.myhdl.org/drpi/32/36_2.png) [@DrPi](https://discourse.myhdl.org/u/DrPi)\
**Post date:** [May 14, 2019, 7:09am UTC](https://discourse.myhdl.org/t/problem-of-async/382/6 "2019-05-14T07:09:22Z")

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You can use Python up to version 3.6.

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<div class="post-metadata">

**Author:** ![azmos](https://avatars.discourse-cdn.com/v4/letter/a/d9b06d/32.png) [@azmos](https://discourse.myhdl.org/u/azmos)\
**Post date:** [May 16, 2019, 6:30pm UTC](https://discourse.myhdl.org/t/problem-of-async/382/7 "2019-05-16T18:30:35Z")

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Thank you. I will try it if I find this version of Python or other previous ones.