public static double ToNumber(object argument) {
XPathNodeIterator it = argument as XPathNodeIterator;
if (it != null) {
return XmlConvert.ToXPathDouble(IteratorToString(it));
}
XPathNavigator nav = argument as XPathNavigator;
if (nav != null) {
return XmlConvert.ToXPathDouble(nav.ToString());
}
return XmlConvert.ToXPathDouble(argument);
}