leetcode 230. Kth Smallest Element in a BST

class Solution(object):    def __init__(self):        self.sequence = list()            def kthSmallest(self, root, k):        """        :type root: TreeNode        :type k: int        :rtype: int        """        self.inorder_travelsal(root,k)        return self.sequence[-1]            def inorder_travelsal(self,root,k):        if not root or len(self.sequence) ==k:            return        self.inorder_travelsal(root.left,k)        if len(self.sequence) != k:            self.sequence.append(root.val)        self.inorder_travelsal(root.right,k)