-(******************************************************************************)
-(* *)
-(* PROJECT HELM *)
-(* *)
-(* Ferruccio Guidi <fguidi@cs.unibo.it> *)
-(* 30/04/2002 *)
-(* *)
-(* *)
-(******************************************************************************)
+(* AUTOR: Ferruccio Guidi <fguidi@cs.unibo.it>
+ *)
+
+type time
+
+val start_time : unit -> time
+
+val stop_time : time -> string
+
+type 'a comparison = Lt
+ | Gt
+ | Eq of 'a