include sig ... end
val arbitrary : unit -> 'aval name : unit -> stringval collapse : t -> t -> boolval lift :
('a -> 'b) ->
[< `Left of 'a | `Right of unit ] ->
[> `Left of 'b | `Right of unit ]val is_bullet : [> `Right of unit ] -> boolval bullet : [> `Right of unit ]val of_vf : 'a -> [> `Left of 'a ]val real_region : t -> bool