show unsym and undef in the aliases example

examples/aliases.csn

@@ -1,10 +1,17 @@
 (
+    (def FOO 777)
+    (undef FOO)
+
     (def FOO 123) ; define a constant
     (call my-add 7 8)
     (cmp res0 138 (ne? (fault "assert failed")))
     (halt)
+    (sym wwww r0)
 
     (proc my-add a b ; give arguments names
+        (sym q r7)
+        (unsym q)
+
         (sym q r0) ; give register a temporary alias
         (add q a b)
         (add q FOO)