val invoke : ('a -> 'b) -> 'a -> unit -> 'bval parallel_map : ('a -> 'b) -> 'a list -> 'b listtype 'a jobs = 'a job listval map_jobs : tasks:int -> 'a jobs -> 'a listval map_batch_jobs : tasks:int -> 'a jobs -> 'a listval backtrace_when_exn : bool ref