Average of Levels in Binary Tree LeetCode solution in Python

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class Solution:
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    def averageOfLevels(self, root: TreeNode) -> List[float]:
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        if not root:
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            # Quick response for empty tree
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            return []
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        traversal_q = [root]
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        average = []
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        while traversal_q:
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            # compute current level average
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            cur_avg = sum((node.val for node in traversal_q if node)) / len(traversal_q)
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            # add to result
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            average.append(cur_avg)
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            # update next level queue
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            next_level_q = [
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                child
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                for node in traversal_q
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                for child in (node.left, node.right)
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                if child
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            ]
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            # update traversal queue as next level's
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            traversal_q = next_level_q
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        return average