private static boolean isNameComparison(XPathExpression op1, XPathExpression op2) {
        if (!isNameFunctionCall(op1)) return false;
        if (!(op2 instanceof XPathString)) {
            return false;
        }
        final String value = ((XPathString)op2).getValue();
        return value != null && value.contains(":");
    }
private static boolean isNameComparison(XPathExpression op1, XPathExpression op2)