How to convert hierarchical array to array for nested sets?

Question

PHP

I have a hierarchical array:

Array
    (
        [0] => Array
            (
                [id] => 28
            )
    
        [1] => Array
            (
                [id] => 29
            )
    
        [2] => Array
            (
                [id] => 30
                [children] => Array
                    (
                        [0] => Array
                            (
                                [id] => 31
                            )
                    )
            )
    )

I need to get left, right and depth keys for nested sets.
I found a similar question on stackoverflow: stackoverflow.com/questions/31744191/php-convert-a...
But, that function in the answer does not work correctly. There is no depth key in it and the calculation of the keys (left and right) is incorrect.
Please tell me how can I solve this problem?