curl --request GET \
  --url https://openapi.pluuug.com/v1/estimate/item/classification \
  --header 'X-API-Key: <api-key>' \
  --header 'X-Signature: <api-key>'

{
  "results": [
    {
      "id": 123,
      "title": "<string>"
    }
  ],
  "next": "http://api.example.org/accounts/?cursor=cD00ODY%3D\"",
  "previous": "http://api.example.org/accounts/?cursor=cj0xJnA9NDg3"
}