aiter, anext not exist error

[Andy963]

Description of the change

solve aiter, anext not exit in pthon 3.9 ,but maybe there is a better way?

Motivation

Type of change

Choose one: (Bug fix | Feature request | Documentation | Other)
bug fix

Checklist

• I have performed a self-review of my code.
• I have added detailed comments to my code where applicable.
• I have verified that my change does not break existing code.
• My PR is based on the latest changes of the main branch (if unsure, please run git pull --rebase upstream main).
• I am familiar with the Google Style Guide for the language I have coded in.
• I have read through the Contributing Guide and signed the Contributor License Agreement.

[Andy963]

@MarkDaoust after more test, I found that even with the implementation of aiter and anext, there could still be some other issues, especially in stream mode.
AttributeError: '_WrappedUnaryStreamCall' object has no attribute '__next__'

[MarkDaoust]

Hi, thanks for reporting back.

Was that with your version of this code?

Can you give me some code snippet to reproduce this?

[MarkDaoust]

SHouldn't the test I enabled in my commit have this case covered?

[MarkDaoust]

I'd like to merge this and roll a new release today.

I'll do some tests on this soon.

[Andy963]

Hi, thanks for reporting back.

Was that with your version of this code?

Can you give me some code snippet to reproduce this?

yes, Your new implemention works fine for me