def test2(self):
root = TreeNode(1)
self.assertEqual([1], caller(root))
def dfs(left, right):
if left > right: return None
mid = (left + right) // 2
return TreeNode(nums[mid], dfs(left, mid - 1), dfs(mid + 1, right))
def test1(self):
root = TreeNode(1)
right = TreeNode(2)
root.right = right
right.left = TreeNode(3)
self.assertEqual([1, 2, 3], caller(root))