text: import { gql } from 'apollo-server-express';
  
  export const typeDefs = gql`
    type Query {
      message: String
      luckyNum: Int
      pi: Float
      graphqlIsCool: Boolean
      author(authorId: ID): Author
      authors: [Author]
      book(bookId: ID): Book
      bookByIsbn(isbn: String): Book
      books: [Book]
      booksByAuthorId(authorId: ID): [Book]
    }
  
    type Mutation {
      appendAuthor(author: NewAuthor): Author
      appendBook(book: NewBook): Book
    }
  
  
    type Author {
        id: ID
        firstName: String
        lastName: String
        phoneNumber: String
        fullName: String
        books: [Book]
    }
  
    type Book {
      id: ID
      isbn: String
      title: String
      authorId: ID
      category: String
      price: Float
      quantity: Int
      author: Author
    }
  
    input NewAuthor {
      firstName: String
      lastName: String
      phoneNumber: String
    }
  
    input NewBook {
      isbn: String
      title: String
      author: NewAuthor
      category: String
      price: Float
      quantity: Int
    }  
  `;
  