code: public String getLabel() {
  		StringBuilder sb = new StringBuilder();
  		try {
  			appendLabel(sb);
  		} catch(IOException e) {
  			throw new AssertionError("Should not happen because using StringBuilder", e);
  		}
  		return sb.toString();
  	}
docs: Gets a short description, useful for links and lists, for this node.
  
  This default implementation calls {@link #appendLabel(java.lang.Appendable)}, thus you *must*
  override at least this method or {@link #appendLabel(java.lang.Appendable)}.
  
  @throws StackOverflowError if {@link #appendLabel(java.lang.Appendable)} not overridden.