leetcode 199. Binary Tree Right Side View

# Definition for a binary tree node.# class TreeNode(object):#     def __init__(self, x):#         self.val = x#         self.left = None#         self.right = Noneclass Solution(object):    def rightSideView(self, root):        """        :type root: TreeNode        :rtype: List[int]        """        """        https://discuss.leetcode.com/topic/16164/5-9-lines-python-48-ms        """        res = list()        if root is not None:            level = [root]            while level:                res.append(level[-1].val)                level = [kid for node in level for kid in (node.left,node.right) if kid]        return res