if (!args[0].isEmpty() && args[0].getItemType() != Type.STRING) throw new XPathException("XPTY0004: namespace URI is of type '" + Type.getTypeName(args[0].getItemType()) + "', 'xs:string' expected");
	public Sequence eval(Sequence[] args, Sequence contextSequence) throws XPathException {        if (context.getProfiler().isEnabled()) {            context.getProfiler().start(this);                   context.getProfiler().message(this, Profiler.DEPENDENCIES, "DEPENDENCIES", Dependency.getDependenciesName(this.getDependencies()));            if (contextSequence != null)                context.getProfiler().message(this, Profiler.START_SEQUENCES, "CONTEXT SEQUENCE", contextSequence);        }                  String namespace;		if (args[0].isEmpty())			namespace = "";		else			namespace = args[0].getStringValue();				String param = args[1].getStringValue();		String prefix = QName.extractPrefix(param);		String localName = QName.extractLocalName(param);		QName qname = new QName(localName, namespace, prefix);		Sequence result = new QNameValue(context, qname);                if (context.getProfiler().isEnabled())             context.getProfiler().end(this, "", result);                 return result;                 	}