include S with type 'a t = 'a forest
Sourceval fold_left : f:('acc -> 'a -> 'acc) -> 'acc -> 'a t -> 'acc
Sourceval iter : f:('a -> unit) -> 'a t -> unit
Sourceval map : f:('a -> 'b) -> 'a t -> 'b t
Sourceval filter_map : f:('a -> 'b option) -> 'a t -> 'b t