--- a/progs/token.scala	Fri Jun 01 16:19:26 2018 +0100
+++ b/progs/token.scala	Sat Jun 09 21:02:04 2018 +0100
@@ -271,8 +271,8 @@
   case c::cs => {
     val rd = der(c, r)     
     val (r_simp, f_simp) = simp(rd)
-    //println(s"BEFORE ${string(rd)}")
-    //println(s"AFTER  ${string(r_simp)}")
+    println(s"BEFORE ${string(rd)}")
+    println(s"AFTER  ${string(r_simp)}")
     val rec = lex_simp(r_simp, cs)
     inj(r, c, f_simp(rec))
   }