public DocumentSet preselect(DocumentSet in_docs, StaticContext context)
public DocumentSet preselect(DocumentSet in_docs)
	public DocumentSet preselect(DocumentSet in_docs, StaticContext context)		throws XPathException {		DocumentSet docs = in_docs;		for (Iterator iter = steps.iterator(); iter.hasNext();)			docs = ((Expression) iter.next()).preselect(docs, context);		return docs;	}