type Author @federation__key(fields: "name") {
  id: ID! @federation__shareable
  name: String!
  articles: [Article]
}

type Article {
  id: ID!
  title: String!
  content: String
  author: Author
}

type Query {
  authors: [Author]
  articles: [Article]
  authorById(id: ID!): Author
  articleById(id: ID!): Article
}

type Mutation {
  addAuthor(name: String!, age: Int): Author
  addArticle(title: String!, content: String, authorId: ID!): Article
}