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

(let res_sink (DataSink 'result))
(let default (lambda '(x) (block '(
   (return (Coalesce x (Default (OptionalItemType (TypeOf x)))))
))))

(let tuple '((Just (Uint32 '1)) (Just (String 'X))))
(let struct (AsStruct '('a (Nothing (OptionalType (DataType 'Uint32)))) '('b (Just (String 'Y)))))

(let world (Write! world res_sink (Key) (StaticMap tuple default) '('('type))))
(let world (Write! world res_sink (Key) (StaticMap struct default) '('('type))))
(let world (Commit! world res_sink))
(return world)
)