XML access question


I’m just messing around with an XML iterator, and I have a simple mapping method, that given a key, maps said key to xml and returns the relevant xml.

Now, it works if I hard code in the XML node that I want to match the key against, but thats not that flexible. So, I want to also be able to pass in the node to match against, but it seems I am getting defeated, by what I thought would be simple.

heres the method I have below;

		public function mapIndex(key:String, xmlNode:*):Object {
   // a nice list of my xml, but its no good if I cant compare it against my key
			trace(xmlNode, _collection.elements(xmlNode)==key);
			return _collection.([xmlNode] == key).length() == 0 ?  _collection[0] :  _collection[_collection.([xmlNode] == key).childIndex()];
     //hard coded below, works fine
    //return _collection.(image == key).length() == 0 ?  _collection[0] :  _collection[_collection.(image == key).childIndex()];

So, what I need to know, is how to get that xmlNode param into the correct datatype for flash to recognise it within an XML child call.