Python 1 Line
\nclass Solution(object):\n    def postorder(self, root):\n        """\n        :type root: Node\n        :rtype: List[int]\n        """\n        return [] if n
```\nclass Solution(object):\n    def postorder(self, root):\n        """\n        :type root: Node\n        :rtype: List[int]\n        """\n        return [] if not root else [j for i in root.children for j in self.postorder(i)] + [root.val]\n```
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