/**
* Evaluate the function to return an iteration of selected nodes.
*/
public SequenceIterator iterate(XPathContext context) throws XPathException {
GenericAtomicComparer comparer = getAtomicComparer(2, context);
SequenceIterator seq = argument[0].iterate(context);
AtomicValue val = (AtomicValue)argument[1].evaluateItem(context);
return new IndexIterator(seq, val, comparer);
}