ThinkPHP中如何将无限级分类的一维数组转换为多维数组？

function getchildarea($id) {
    // ... 代码略 ...
}

[
    ['id' => 1, 'area_name' => '安徽省', 'pid' => 0, 'level' => 1],
    ['id' => 4, 'area_name' => '合肥市', 'pid' => 1, 'level' => 2],
    ['id' => 7, 'area_name' => '肥东县', 'pid' => 4, 'level' => 3],
    ['id' => 8, 'area_name' => '桃园镇', 'pid' => 7, 'level' => 4],
    ['id' => 9, 'area_name' => '八斗乡', 'pid' => 8, 'level' => 5],
    ['id' => 10, 'area_name' => '长丰县', 'pid' => 4, 'level' => 3]
]

function deal_list_to_tree($data) {
    // ... 代码略 ...
}

[
    ['id' => 1, 'area_name' => '安徽省', 'pid' => 0, 'level' => 1, 'children' => [
        ['id' => 4, 'area_name' => '合肥市', 'pid' => 1, 'level' => 2, 'children' => [
            ['id' => 7, 'area_name' => '肥东县', 'pid' => 4, 'level' => 3, 'children' => [
                ['id' => 8, 'area_name' => '桃园镇', 'pid' => 7, 'level' => 4, 'children' => []],
                ['id' => 9, 'area_name' => '八斗乡', 'pid' => 8, 'level' => 5, 'children' => []]
            ]],
            ['id' => 10, 'area_name' => '长丰县', 'pid' => 4, 'level' => 3, 'children' => []]
        ]]
    ]]
]