<img width="298" alt="スクリーンショット 2023-05-29 16 30 33" src="https://github.com/soutaro/steep/assets/139089/cba04404-4b58-4c33-a4ba-0e18250747a6"> Where the type of `set` is expected to be `Set[Integer]` ...
