{
  stations {
    name
    code
  }
}

{
  "data": {
    "stations": [
      {
        "name": "Station1",
        "code": "ST1"
      },
      {
        "name": "Station2",
        "code": "ST2"
      },
    ]
}

{
    stations(code: "ST1") {
     name
     code
    }
}

{
    "errors": [
        {
            "message": "Unknown argument "code" on field "stations" of type "RootQuery".",
            "locations": [
                {
                    "line": 2,
                    "column": 11
                }
            ]
        }
    ]
}