schema {
  query: Query,
  mutation: Mutation
}

type Query {
  bookById(id: ID): Book
}

type Mutation {
  addBook(bookInput: BookInput): Book
}

type Book {
  id: ID
  name: String
  author: Author
}

type Author {
  id: ID
  name: String
}

input BookInput {
  name: String
  authorId: ID
}
