Simple Recursive Solution
\nclass Solution:\n    def postorder(self, root: \'Node\') -> List[int]:\n        if not root:\n            return []\n        children = []\n        for node i
```\nclass Solution:\n    def postorder(self, root: \'Node\') -> List[int]:\n        if not root:\n            return []\n        children = []\n        for node in root.children:\n            children += self.postorder(node)\n        return children + [root.val]\n```
['Python']