[Question] Topics API

Hello everyone!

I did not find any **topics** API implementation (yeah, I know it's in preview) but I need that API for the personal purpose so I implemented it by myself.

Should I make a **PR**?

Thanks.

No file, test, or entry point is named. First review the repository's existing GitHub API wrapper structure and the Topics API requirements, then seek maintainer agreement on scope; this question has had no recent response.

索引モデルが issue の本文から書いたものです。