--- a/progs/matcher/re3.sc	Sun Oct 02 08:42:01 2022 +0100
+++ b/progs/matcher/re3.sc	Sun Oct 09 13:39:34 2022 +0100
@@ -65,6 +65,7 @@
 }
 
 
+
 // the derivative w.r.t. a string (iterates der)
 def ders(s: List[Char], r: Rexp) : Rexp = s match {
   case Nil => r