ydb/yql/essentials/tests/s-expressions/suites/Optimizers/MapNextWithUnusedNext.yqls

(
(let config (DataSource 'config))

(let lst (AsList (Int32 '0) (Int32 '1) (Int32 '2) (Int32 '3)))
(let lst (Iterator lst))
(let lst (MapNext lst (lambda '(current next) (+ current (Int32 '1)))))
(let lst (ForwardList lst))

(let res_sink (DataSink 'result))
(let world (Write! world res_sink (Key) lst '('('type))))
(let world (Commit! world res_sink))
(return world)
)