query nullableStringArg($nonNullableVar: String!, $nonNullableList: [String!]!, $nonNullableListList: [[Int!]!]) {
  arguments {
    nullableString(nullableString: $nonNullableVar)
    nullableList(nullableList: $nonNullableList)
    nullableListList(nullableListList: $nonNullableListList)
  }
}

type Query {
  arguments: Arguments
}

type Arguments {
  nullableString(nullableString: String): String
  nullableList(nullableList: [String]): String
  nullableListList(nullableListList: [[Int]]): Int
}