Sequence seq = expression.eval(docs, contextSequence, contextItem);
Sequence seq = expression.eval(contextSequence, contextItem);
	public Sequence eval(		DocumentSet docs,		Sequence contextSequence,		Item contextItem)		throws XPathException {		// declare the variable		Variable var = new Variable(QName.parse(context, qname));		Sequence seq = expression.eval(docs, contextSequence, contextItem);		if(sequenceType != null) {			sequenceType.checkType(seq.getItemType());			sequenceType.checkCardinality(seq);		}		var.setValue(seq);		context.declareVariable(var);		return Sequence.EMPTY_SEQUENCE;	}