function getBook(bookId) {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      let book = {
        title: ‘JavaScript’,
        authorId: ‘123’
      }
    
      resolve(book);
    }, 500);
  });
}
function getAuthor(authorId) {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      let author = {
        name: ‘Amy’,
        age: 28
      }
      resolve(author);
    }, 500);
  });
}
async function fetchData() {
  let book = await getBook(2020);
  let author = await getAuthor(book.authorId);
  console.log(author)
}
fetchData(); // { name: ‘Amy’, age: 28 }