module Id:sig..end
type'at ='a
val return : 'a -> 'aval bind : 'a -> ('a -> 'b) -> 'bval fail : exn -> 'aval catch : (unit -> 'a) -> (exn -> 'a) -> 'aval finalize : (unit -> 'a) -> (unit -> 'b) -> 'aval sleep : float -> unitval auto_yield : 'a -> unit -> unit