--- a/progs/re1.scala	Sat May 05 10:31:00 2018 +0100
+++ b/progs/re1.scala	Fri Jun 01 15:28:37 2018 +0100
@@ -50,10 +50,10 @@
 der('b', r)
 der('c', r)
 
-val r = SEQ(SEQ(CHAR('x'), CHAR('y')), CHAR('z'))
-der('x', r)
-der('y', der('x', r))
-der('z', der('y', der('x', r)))
+val r2 = SEQ(SEQ(CHAR('x'), CHAR('y')), CHAR('z'))
+der('x', r2)
+der('y', der('x', r2))
+der('z', der('y', der('x', r2)))
 
 
 //optional regular expression (one or zero times)