'Return items (excluding top level items)'

def get_items(self):

    itemlist = []
    def add_to_itemlist(item):
        for index in range(item.childCount()):
            citem = item.child(index)
            itemlist.append(citem)
            add_to_itemlist(citem)
    for tlitem in self.get_top_level_items():
        add_to_itemlist(tlitem)
    return itemlist
