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

(
(let config (DataSource 'config))

(let data (Length (List (ListType (DataType 'String)) (String 'a) (String 'b))))
(let res_sink (DataSink 'result))
(let world (Write! world res_sink
    (Key)
    data '('('type))))

(let world (Commit! world res_sink))
(return world)
)