curl --request GET \
  --url https://api.example.com/v1/convert/volume/gal-us-to-l \
  --header 'X-API-Key: <api-key>'

{
  "detail": [
    {
      "loc": [
        "<string>"
      ],
      "msg": "<string>",
      "type": "<string>"
    }
  ]
}