ydb/yql/essentials/tests/s-expressions/suites/Optimizers/Condense1OneItemTuple.yqls

(
(let config (DataSource 'config))

(let list (AsList (String 'a) (String 'b) (String 'c)))
(let data (Condense1 list
   (lambda '(item)
       '(item))
   (lambda '(item state) (Bool 'false))
   (lambda '(item state) (block '(
      (let x (Concat (Nth state '0) item))
      (return '(x)))))))
(let res_sink (DataSink 'result))
(let world (Write! world res_sink
    (Key)
    data '('('type))))

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