(
(let config (DataSource 'config))

(let res_sink (DataSink 'result))
(let myStruct (AsStruct '('a (String 'z)) '('b (Null))))
(let typeOfMyStruct (TypeOf myStruct))

(let world (Write! world res_sink (Key) (Member (Just myStruct) 'b) '('('type))))
(let world (Write! world res_sink (Key) (Member (Nothing (OptionalType typeOfMyStruct)) 'b) '('('type))))
(let world (Commit! world res_sink))
(return world)
)