curl --request PUT \
  --url http://localhost/api/v3/regions/{region} \
  --header 'Content-Type: application/json' \
  --data '
{
  "name": "<string>",
  "is_default": true,
  "currency": "<string>",
  "countries": [
    {
      "iso_2": "<string>",
      "iso_3": "<string>",
      "iso_numeric": "<string>"
    }
  ]
}
'

{
  "data": {
    "id": 123,
    "name": "<string>",
    "handle": "<string>",
    "countries": [
      {
        "id": 123,
        "name": "<string>",
        "iso_2": "<string>",
        "iso_3": "<string>",
        "iso_numeric": "<string>",
        "sort_order": 123,
        "states": [
          {
            "id": 123,
            "name": "<string>",
            "type": "<string>",
            "iso": "<string>",
            "iso_2_country": "<string>",
            "iso_2_country_state_code": "<string>",
            "sort_order": 123,
            "created_at": "<string>",
            "updated_at": "<string>"
          }
        ],
        "currency": "<string>",
        "created_at": "<string>",
        "updated_at": "<string>",
        "region": {
          "id": "<string>",
          "name": "<string>",
          "handle": "<string>",
          "is_default": "<string>"
        }
      }
    ],
    "is_default": true,
    "currency": "<string>",
    "created_at": "<string>",
    "updated_at": "<string>"
  }
}