+let time f x =
+ let t1 = Unix.gettimeofday () in
+ let r = f x in
+ let t2 = Unix.gettimeofday () in
+ let t = (1000. *.(t2 -. t1)) in
+ Printf.eprintf " %fms\n%!" t ;
+ r
+;;
+let _ = Printf.eprintf "Timing traversal ... ";;
+let _ = time (full_traversal) doc
+;;