Python Solution
Python\n\ndef postorder(self, root: \'Node\') -> List[int]:\n        if not root: return\n        \n        def pst(r, l=[]):\n            if r.children:\n     
Python\n```\ndef postorder(self, root: \'Node\') -> List[int]:\n        if not root: return\n        \n        def pst(r, l=[]):\n            if r.children:\n                for c in r.children:\n                    pst(c, l)\n            l.append(r.val)\n            return l\n            \n        return pst(root)\n```
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