Binary Tree Pruning LeetCode solution in Python

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class Solution:
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    def pruneTree(self, root):
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        """
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        :type root: TreeNode
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        :rtype: TreeNode
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        """
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        if not root:
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            return root
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        root.left, root.right = self.pruneTree(root.left), self.pruneTree(root.right)
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        return None if not root.val and not root.left and not root.right else root