ydb/yql/essentials/tests/s-expressions/suites/Stream/CombineCore.yqls

(
#comment
(let config (DataSource 'config))
(let res_sink (DataSink 'result))
(let stream (Iterator (AsList (Int32 '1) (Int32 '2) (Int32 '3))))
(let keyExtractor (lambda '(item) item))
(let init (lambda '(key item) item))
(let update (lambda '(key item state) (+ item state)))
(let finish (lambda '(key state) (Just state)))
(let data (Sort (Collect (CombineCore stream keyExtractor init update finish)) (Bool 'true) keyExtractor))
(let world (Write! world res_sink (Key) data '('('type))))
(let world (Commit! world res_sink))
(return world)
)