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

(let res_sink (DataSink 'result))
(let list (AsList
  (AsStruct '('key (Just (Uint32 '1))) '('value (String 'a)))
  (AsStruct '('key (Nothing (OptionalType (DataType 'Uint32)))) '('value (String 'a)))
))

(let world (Write! world res_sink (Key) (SkipNullMembers list '('key)) '('('type))))
(let world (Commit! world res_sink))
(return world)
)