Construct Binary Search Tree from Preorder Traversal LeetCode solution in Python

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class Solution:
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    def bstFromPreorder(self, preorder: List[int]) -> Optional[TreeNode]:
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        if not preorder:
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            return None
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        node = preorder.pop(0)
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        root = TreeNode(node)
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        l = []
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        r = []
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        for val in preorder:
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            if val < node:
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                l.append(val)
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            else:
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                r.append(val)
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        root.left = self.bstFromPreorder(l)
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        root.right = self.bstFromPreorder(r)
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        return root