List<Cell> existingList = params.getPrefetchedList(rowKey, column.name);
int idx = ByteBufferUtil.toInt(index);
if (idx < 0 || idx >= existingList.size())
throw new InvalidRequestException(String.format("List index %d out of bound, list has size %d", idx, existingList.size()));
CellName elementName = existingList.get(idx).name();
if (value == null)
{
cf.addColumn(params.makeTombstone(elementName));
}
else