Count Good Nodes in Binary Tree LeetCode solution in Python

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class Solution:
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    def goodNodes(self, root: TreeNode) -> int:
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        # Our counter for the good nodes.
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        count = 0
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        def helper(node, m):
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            nonlocal count
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            # If we run out of nodes return.
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            if not node:
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                return
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            # If the current node val is >= the largest observed in the path thus far.
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            if node.val >= m:
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                # Add 1 to the count and update the max observed value.
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                count += 1
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                m = max(m, node.val)
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            # Traverse l and r subtrees.
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            helper(node.left, m)
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            helper(node.right, m)
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        helper(root, root.val)
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        return count