--- a/PrimaryNode.st	Mon Apr 23 22:41:47 2018 +0200
+++ b/PrimaryNode.st	Mon Apr 23 22:42:08 2018 +0200
@@ -1,3 +1,5 @@
+"{ Encoding: utf8 }"
+
 "
  COPYRIGHT (c) 1989 by Claus Gittinger
 	      All Rights Reserved
@@ -88,6 +90,13 @@
     ^ self subclassResponsibility
 ! !
 
+!PrimaryNode methodsFor:'enumeration'!
+
+allSubNodesDo:aBlock
+    "no subnodes"
+
+    ^ self
+! !
 
 !PrimaryNode methodsFor:'evaluation'!