curl --request GET \
  --url https://api.kadoa.com/v4/variables/{variableId} \
  --header 'x-api-key: <api-key>'

{
  "variable": {
    "id": "<string>",
    "key": "<string>",
    "value": "<string>",
    "createdAt": "<string>",
    "dataType": "STRING",
    "updatedAt": "<string>"
  },
  "error": "<string>"
}