+
+ static Topology toAtom(Element e) {
+ if (e instanceof Atom) return (Atom)e;
+ if (e instanceof Sequence) return ((Sequence)e).toAtom();
+ Topology ret = null;
+ for(Sequence s : (Union)e)
+ ret = ret==null ? toAtom(s) : ret.union(s.toAtom());
+ return ret;
+ }