我有一个多维数组，我试图找出如何简单地“回显”数组中的元素。数组的深度未知，因此可以深度嵌套。

对于下面的数组，正确的回显顺序为：

This is a parent comment
This is a child comment
This is the 2nd child comment
This is another parent comment

这是我正在谈论的数组：

Array
(
    [0] => Array
        (
            [comment_id] => 1
            [comment_content] => This is a parent comment
            [child] => Array
                (
                    [0] => Array
                        (
                            [comment_id] => 3
                            [comment_content] => This is a child comment
                            [child] => Array
                                (
                                    [0] => Array
                                        (
                                            [comment_id] => 4
                                            [comment_content] => This is the 2nd child comment
                                            [child] => Array
                                                (
                                                )
                                        )
                                )
                        )
                )
        )

    [1] => Array
        (
            [comment_id] => 2
            [comment_content] => This is another parent comment
            [child] => Array
                (
                )
        )
)