/// <summary>
/// Retrieves the value of the attribute having the given name, or <c>null</c> if there is no such attribute.
/// </summary>
/// <param name="element"></param>
/// <param name="name"></param>
/// <returns></returns>
public static string AttributeValue(this IXPathNavigable element, XName name)
{
return(element.AttributeValueOpt(name).SingleOrDefault());
}