Fix flake8 error

[KumoLiu]

Fixes #1617

Checks

• Avoid including large-size files in the PR.
• Clean up long text outputs from code cells in the notebook.
• For security purposes, please check the contents and remove any sensitive info such as user names and private key.
• Ensure (1) hyperlinks and markdown anchors are working (2) use relative paths for tutorial repo files (3) put figure and graphs in the ./figure folder
• Notebook runs automatically ./runner.sh -t <path to .ipynb file>

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[ericspod]

Hi @KumoLiu I see a few formatting issues that are unrelated to the fix but are important to undo. I see a number of other changes in the JSON for these notebooks, I don't know if it's an issue or not however. Looks good otherwise, thanks.

[KumoLiu]

Hi @KumoLiu I see a few formatting issues that are unrelated to the fix but are important to undo. I see a number of other changes in the JSON for these notebooks, I don't know if it's an issue or not however. Looks good otherwise, thanks.

Hi @ericspod, yes. they are changed by the autofix, I will revert them today. Thanks.

[ericspod]

I might have flagged issues again before you had a chance to get them, ignore later comments if so!

[ericspod]

Looks good now!