(
#comment
(let config (DataSource 'config))

(let res_sink (DataSink 'result))
(let udf (Udf 'SimpleUdf.Echo))
(let data (Map (AsList (String 'a) (String 'b)) udf))
(let world (Write! world res_sink (Key) data '('('type))))
(let world (Commit! world res_sink))
(return world)
)