At the moment I have something like:

```
arr = [
  :name,
  :address,
  cards_attributes: [
    :last_name,
    :first_name,
    phones_attributes: [
      :number,
      :_destroy
    ],
    emails_attributes: [
      :number,
      :_destroy
    ],
    ...
  ]
]

```

... and I want to turn it into something like:

```
arr = [
  :id, # <- new!
  :name,
  :address,
  cards_attributes: [
    :id, # <- new!
    :last_name,
    :first_name,
    phones_attributes: [
      :id, # <- new!
      :number,
      :_destroy
    ],
    emails_attributes: [
      :id, # <- new!
      :number,
      :_destroy
    ],
    ...
  ]
]

```

I know I can add a new symbol to the first level with `arr.push(:id)` but how do I add elements into the sub hashes?