assuming an N-th dimensional array, eg.

```js
const array = [
  "1",
  ["2","2"],
  [["3","3"],["3","3"]],
  [
    [
      [["4","4"],"3"],
      [["4","4"],"3"]
    ],
  ],
  [["3","3"],["3","3"]],
  ["2","2"],
  "1"
];

```

I can only find methods to flatten arrays from shallow-end of the index up, but I need to flatten/reduce or otherwise handle only the deepest (or any arbitrary) index level.

When running the deepest level I am looking for an array output something along the lines of

```
array = [
  "1",
  ["2","2"],
  [["3","3"],["3","3"]],
  [
    [
      ["4,4","3"],
      ["4,4","3"]
    ],
  ],
  [["3","3"],["3","3"]],
  ["2","2"],
  "1"
];

```

I cannot find a solution that isn't garbage... (over-complicated/incredibly messy)
Any help would be appreciated