<!-- Release notes generated using configuration in .github/release.yml at master -->
What's Changed
There are several keywords that can be used for the properties of Template Messages and Flex Messages.
Starting from this version, these keywords are provided. In addition to keywords, you can use strings that specify percentages or pixels, so please convert the keywords to strings if necessary. The original definitions are also written in [Flex Message layout](https://developers.line.biz/en/docs/messaging-api/flex-message-layout/) and https://github.com/line/line-openapi/pull/46.
line-openapi updates
* chore(deps): update line-openapi digest to 16f6311 by renovate in https://github.com/line/line-bot-sdk-python/pull/580
* Codes are generated by openapi generator by github-actions in https://github.com/line/line-bot-sdk-python/pull/581
Other Changes
* Enhance Documentation for Response and Error Handling in SDK by Yang-33 in https://github.com/line/line-bot-sdk-python/pull/579
**Full Changelog**: https://github.com/line/line-bot-sdk-python/compare/3.6.0...3.7.0