* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*)
+val nprocs : unit -> int
+(** Return the number of processors on the system. *)
+
val failwithf : ('a, unit, string, 'b) format4 -> 'a
(** Like [failwith] but supports printf-like arguments. *)
val is_directory : string -> bool
(** Return true iff parameter is a directory. *)
+val unique : unit -> int
+(** Returns a unique number each time called. *)
+
val filter_map : ('a -> 'b option) -> 'a list -> 'b list
(** [filter_map f l] applies [f] to every element of [l], filters
out the [None] elements and returns the list of the arguments of