List<Item> items = new RssReader().read("file:/path/to/file").toList();

List<String> sources = List.of(
   "file:/path/to/file",
   "https://www.nasa.gov/news-release/feed/",
   "file:///path/to/another/file",
   "https://www.engadget.com/rss.xml"));

List<Item> items = new RssReader().read(sources).toList();