Show HN: rssc – RSS (atom and JSON too) customizer

I've used https://hnrss.github.io/ (HN rss) for a while, which provided some customization over queries; however, it was limited to OR predicates only. Sometimes I wished to have more extensible RSS preferences; some of the feed readers I used supported such advanced queries, but the majority didn't. Using this approach, customization is possible on any atom, RSS, or JSON feed using regex expressions to filter feed entities based on title, description, content, and authors. Examples are provided on the article link.