力扣 94 题 内置的left 函数要怎么弄呢 AttributeError: 'list' object has no attribute 'left'

力扣 94 题 内置的left 函数要怎么弄呢

我这边有报错 AttributeError: 'list' object has no attribute 'left'
但是这个在Leetcode界面上面 是没有问题的 所以应该是 有内置的函数left了

from typing import List

class TreeNode:
def init(self, val=0, left=None, right=None):
self.val = val
self.left = left
self.right = right

class Solution:
def inorderTraversal(self, root: TreeNode) -> List[int]:
result = []
self.helper(root, result)
return result

def helper(self, node, result):
    if node is None:
        return
    self.helper(node.left, result)
    result.append(node.val)
    self.helper(node.right, result)

if name == 'main':
root = [1,2,3,4,5,6,7]
r = Solution().inorderTraversal(root)
print(r)