enum City {
  Athens
  Sparta
  Corinth
  delphi
  Argos
  Ithaca
}

input UserInput {
  name: ID!
}

type User {
  name: String!
  home: City
}

type Query {
  user(user: UserInput): User
  city(city: City!): City!
  cities: [City!]!
}