fix by ruff

[YoshitakaNaraoka]

Thank you for opening a Pull Request! Before submitting your PR, there are a few things you can do to make sure it goes smoothly:

• [ ] Make sure to open an issue as a bug/issue before writing your code! That way we can discuss the change, evaluate designs, and agree on the general idea
• [x] Ensure the tests and linter pass
• [x] Code coverage does not decrease (if any source code was changed)
• [ ] Appropriate docs were updated (if necessary)

Fixes #<issue_number_goes_here> 🦕

[google-cla[bot]]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

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[parthea]

Hi @YoshitakaNaraoka, Thanks for opening a PR. Please could you sign the CLA?

[YoshitakaNaraoka]

I don't know how to do it. @parthea

[parthea]

View this failed invocation of the CLA check for more information.

If you are not currently covered under a CLA, please visit https://cla.developers.google.com/. Once you've signed, follow the "New Contributors" link at the bottom of that page to update this check.

[YoshitakaNaraoka]

I already 署名 cla

[parthea]

Regrettably, the CLA status is still not satisfied. Please can you double check the email address used for the CLA?

***@hotmail.com Need CLA