Construct Quad Tree LeetCode solution in Python

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"""
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# Definition for a QuadTree node.
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class Node:
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    def __init__(self, val, isLeaf, topLeft, topRight, bottomLeft, bottomRight):
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        self.val = val
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        self.isLeaf = isLeaf
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        self.topLeft = topLeft
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        self.topRight = topRight
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        self.bottomLeft = bottomLeft
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        self.bottomRight = bottomRight
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"""
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class Solution:
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    def construct(self, grid: List[List[int]]) -> "Node":
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        def is_grid_a_leaf(mylist, n):
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            x = mylist[0][0]
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            for i in range(n):
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                for j in range(n):
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                    if mylist[i][j] != x:
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                        return (0, 0)
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            return (1, x)
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        def tree_builder(currlist) -> "Node":
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            node = Node()
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            n = len(currlist)
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            node.isLeaf, node.val = is_grid_a_leaf(currlist, n)
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            if node.isLeaf:
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                node.topLeft = node.topRight = node.bottomLeft = node.bottomRight = None
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            else:
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                top_left = [
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                    [row[i] for i in range(n // 2)] for row in currlist[0 : n // 2]
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                ]
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                top_right = [
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                    [row[i] for i in range(n // 2, n)] for row in currlist[0 : n // 2]
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                ]
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                bot_left = [
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                    [row[i] for i in range(n // 2)] for row in currlist[n // 2 : n]
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                ]
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                bot_right = [
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                    [row[i] for i in range(n // 2, n)] for row in currlist[n // 2 : n]
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                ]
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                node.topLeft = tree_builder(top_left)
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                node.topRight = tree_builder(top_right)
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                node.bottomLeft = tree_builder(bot_left)
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                node.bottomRight = tree_builder(bot_right)
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            return node
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        return tree_builder(grid)