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

(let res_sink (DataSink 'result))
(let t (AsList
  (String 'a)
  (String 'b)
))

(let jt (Just t))
(let n (Nothing (TypeOf jt)))

(let world (Write! world res_sink (Key) (ToIndexDict jt) '('('type))))
(let world (Write! world res_sink (Key) (ToIndexDict n) '('('type))))

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