docs: Fix example codes

[massongit]

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• Fill out the template below. Any pull request that does not include enough information to be reviewed in a timely manner may be closed at the maintainers' discretion.
• The pull request must update the test suite to demonstrate the changed functionality.
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Description of the Change

import statements and indentation of example codes listed in README.md is incorrect. Therefore, I will correct it.

Issue or RFC

Alternate Designs

Possible Drawbacks

Verification Process

Release Notes

• Fix import statements and indentation of example codes listed in README.md

[coveralls]

coverage: 83.628%. remained the same when pulling df38276b995ddaea94acc1f48adb50422ec598c2 on massongit:fix_code into e92208fc39c5064ec5236decb59864280b707ee3 on yitsushi:main.