--- a/progs/app3.scala	Tue Sep 24 01:12:36 2013 +0100
+++ b/progs/app3.scala	Tue Sep 24 01:56:53 2013 +0100
@@ -4,7 +4,7 @@
   if (n == 0) ()
   else if (my_urls.findFirstIn(url) == None) ()
   else {
-    println("Visiting: " + n + " " + url)
+    println(s"Visiting: $n $url")
     for (u <- get_all_URLs(get_page(url))) crawl(u, n - 1)
   }
 }