Please let me know if there are something can be improved:)

```
# Definition for a binary tree node.
# class TreeNode(object):
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution(object):
def levelOrderBottom(self, root):
"""
:type root: TreeNode
:rtype: List[List[int]]
"""
if root == None:
return []
queue, res = [root], []
while not len(queue) == 0:
values, temp = [], []
for node in queue:
if not node.left == None:
temp += [node.left]
if not node.right == None:
temp += [node.right]
values += [node.val]
res = [values] + res
queue = temp
return res
```