python list.reverse() 与 list[::-1] 的区别

这两个操作功能一直，但 list.reverse() 没有返回值

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def levelOrderBottom(self, root: TreeNode) -> List[List[int]]:
        if not root:
            return []

        from collections import deque
        que = deque([root])
        results = []
        while(que):
            size = len(que)
            res = []
            for _ in range(size):
                cur = que.popleft()
                res.append(cur.val)
                if cur.left:
                    que.append(cur.left)
                if cur.right:
                    que.append(cur.right)
            results.append(res)
            
        # return results.reverse() #直接这么写会报错
        
        results.reverse()

        return results