Jsonable.S3
type ('a, 'b, 'c) t
val to_yojson : 'a jsonable -> 'b jsonable -> 'c jsonable -> ( 'a, 'b, 'c ) t jsonable
val of_yojson : 'a maybe_json -> 'b maybe_json -> 'c maybe_json -> ( 'a, 'b, 'c ) t maybe_json