def get_items(self, maxlevel):
        """Return all items with a level <= `maxlevel`"""
        itemlist = []
        def add_to_itemlist(item, maxlevel, level=1):
            level += 1
            for index in range(item.childCount()):
                citem = item.child(index)
                itemlist.append(citem)
                if level <= maxlevel:
                    add_to_itemlist(citem, maxlevel, level)
        for tlitem in self.get_top_level_items():
            itemlist.append(tlitem)
            if maxlevel > 0:
                add_to_itemlist(tlitem, maxlevel=maxlevel)
        return itemlist
Return all items with a level <= `maxlevel`