Sequence seq = expression.eval(docs, contextSequence, contextItem);
Sequence seq = expression.eval(contextSequence, contextItem);
	public Sequence eval(DocumentSet docs, Sequence contextSequence, Item contextItem)		throws XPathException {		if (contextItem != null)			contextSequence = contextItem.toSequence();		Sequence seq = expression.eval(docs, contextSequence, contextItem);		if (seq.getLength() == 0)			return seq;		setContext(seq);		Predicate pred;		Sequence result = seq;		for (Iterator i = predicates.iterator(); i.hasNext();) {			pred = (Predicate) i.next();			result = pred.eval(docs, result);		}		return result;	}