////////////////////////////////////////////////////////////////////////////////
+ public Element noFollow = null;
+ public final Topology noFollow() { return noFollow==null ? null : noFollow.toAtom(); }
+
+ Topology toAtom() {
+ if (elements.length!=1) throw new RuntimeException("cannot invoke toAtom() on a Sequence with " + elements.length + " elements: " + this);
+ return elements[0].toAtom();
+ }
+
protected final Element[] elements;
final HashSet<Sequence> needs;