+ protected String left() { return "{"; }
+ protected String right() { return "}"; }
+ protected boolean ignoreSingleton() { return false; }
+
+ public GraphViz.Node toGraphViz(GraphViz gv) {
+ if (gv.hasNode(this)) return gv.createNode(this);
+ GraphViz.Node n = gv.createNode(this);
+ n.label = head()==null ? "" : head().toString();
+ //n.color = "red";
+ for(Tree t : this) n.edge(t, null);
+ return n;
+ }
+ public boolean isTransparent() { return false; }
+ public boolean isHidden() { return false; }