X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FSequence.java;h=e18f5efc5ca56271fa6e225e75e0bf07d7062cbd;hp=9586f728e1e5df391de200cfd00d1c090b751e2d;hb=242a8711e98cbd3ed6d05271bf910fde38e9be9a;hpb=2690f6c749f117a103c57d651d89f1b4fbf1316d

diff --git a/src/edu/berkeley/sbp/Sequence.java b/src/edu/berkeley/sbp/Sequence.java
index 9586f72..e18f5ef 100644
--- a/src/edu/berkeley/sbp/Sequence.java
+++ b/src/edu/berkeley/sbp/Sequence.java
@@ -35,8 +35,11 @@ public abstract class Sequence extends Element implements Iterable<Element> {
 
     ////////////////////////////////////////////////////////////////////////////////
 
+    public Element noFollow = null;
+    public final Topology noFollow() { return noFollow==null ? null : noFollow.toAtom(); }
+
     Topology toAtom() {
-        if (elements.length!=1) return null;
+        if (elements.length!=1) throw new RuntimeException("cannot invoke toAtom() on a Sequence with " + elements.length + " elements: " + this);
         return elements[0].toAtom();
     }