public Sequence eval(DocumentSet docs, Sequence contextSequence, Item contextItem) throws XPathException {
public Sequence eval(Sequence contextSequence, Item contextItem) throws XPathException {
	public Sequence eval(DocumentSet docs, Sequence contextSequence, Item contextItem) throws XPathException {		if(contextItem != null)			contextSequence = contextItem.toSequence();		Sequence s1 = getArgument(0).eval(docs, contextSequence);		Sequence s2 = getArgument(1).eval(docs, contextSequence);		if(s1.getLength() == 0 || s2.getLength() == 0)			return Sequence.EMPTY_SEQUENCE;		if(s1.getStringValue().startsWith(s2.getStringValue()))			return BooleanValue.TRUE;		else			return BooleanValue.FALSE;	}