如何恢复QTreeView上次扩展状态？

def save_expanded_state(tree_view, item=None):
    if item is None:
        item = tree_view.invisibleRootItem()

    expanded_state = []
    for i in range(item.childCount()):
        child = item.child(i)
        expanded_state.append(child.isExpanded())
        expanded_state += save_expanded_state(tree_view, child)

    return expanded_state

def restore_expanded_state(tree_view, item=None, expanded_state=None):
    if item is None:
        item = tree_view.invisibleRootItem()

    if expanded_state is None:
        expanded_state = []

    for i in range(item.childCount()):
        child = item.child(i)
        if expanded_state:
            child.setExpanded(expanded_state.pop(0))
        restore_expanded_state(tree_view, child, expanded_state)

# 保存展开状态
expanded_state = save_expanded_state(self.tree_view)

# 恢复展开状态
restore_expanded_state(self.tree_view, expanded_state=expanded_state)