if(var == null) { var = (Variable) globalVariables.get(qn); }
	public Variable resolveVariable(String qname) throws XPathException {		QName qn = QName.parse(this, qname);		Variable var = (Variable) variables.get(qn);		if (var == null)			throw new XPathException("variable " + qname + " is not bound");		return var;	}