code: def set_children(self, item, *newchildren):
          
          self._visual_drag.set_children(item, *newchildren)
          ttk.Treeview.set_children(self, item, *newchildren)
docs: Replaces item’s children with newchildren.
  
          Children present in item that are not present in newchildren are detached
          from tree. No items in newchildren may be an ancestor of item.
  
          :param newchildren: new item's children (list of item identifiers)
          :type newchildren: sequence[str]