<span>leetcode-94 Binary Tree Inorder Traversal</span>

 1 # Definition for a binary tree node.
 2 # class TreeNode:
 3 #     def __init__(self, val=0, left=None, right=None):
 4 #         self.val = val
 5 #         self.left = left
 6 #         self.right = right
 7 class Solution:
 8     def inOrder(self, root, arr):
 9         if root != None:
10             self.inOrder(root.left, arr)
11             arr.append(root.val)
12             self.inOrder(root.right, arr)
13         return arr
14     def inorderTraversal(self, root: TreeNode) -> List[int]:
15         arr = []
16         arr = self.inOrder(root, arr)
17         return arr