return getArgument(0).eval(context, docs, contextSequence, null).convertTo(Type.BOOLEAN);
contextSequence = getArgument(0).eval(docs, contextSequence); return contextSequence.effectiveBooleanValue() ? BooleanValue.TRUE : BooleanValue.FALSE;
	public Sequence eval(StaticContext context, DocumentSet docs, Sequence contextSequence,		Item contextItem) throws XPathException {		if(contextItem != null)			contextSequence = contextItem.toSequence();		return 			getArgument(0).eval(context, docs, contextSequence, null).convertTo(Type.BOOLEAN);	}