curl --request GET \
  --url https://api.siftstack.com/api/v1/calculated-channels:expression-identifiers \
  --header 'Authorization: Bearer <token>'

{
  "identifiers": [
    {
      "name": "<string>",
      "description": "<string>",
      "type": "EXPRESSION_IDENTIFIER_TYPE_UNSPECIFIED",
      "displayName": "<string>",
      "library": "EXPRESSION_IDENTIFIER_LIBRARY_UNSPECIFIED"
    }
  ],
  "nextPageToken": "<string>"
}