public Sequence eval(StaticContext context, DocumentSet docs, Sequence contextSequence, Item contextItem) throws XPathException { Sequence lval = left.eval(context, docs, contextSequence, contextItem); Sequence rval = right.eval(context, docs, contextSequence, contextItem);
public Sequence eval(DocumentSet docs, Sequence contextSequence, Item contextItem) throws XPathException { Sequence lval = left.eval(docs, contextSequence, contextItem); Sequence rval = right.eval(docs, contextSequence, contextItem);
	public Sequence eval(StaticContext context, DocumentSet docs, Sequence contextSequence, 		Item contextItem) throws XPathException {		Sequence lval = left.eval(context, docs, contextSequence, contextItem);		Sequence rval = right.eval(context, docs, contextSequence, contextItem);		if(lval.getItemType() != Type.NODE || rval.getItemType() != Type.NODE)			throw new XPathException("union operand is not a node sequence");        NodeSet result = ((NodeSet)lval).union((NodeSet)rval);		return result;	}