How to use the sapper function in sapper

import polka from 'polka';
import compression from 'compression';
import sapper from 'sapper';
import serve from 'serve-static';
import { Store } from './store.js';
import { routes } from './manifest/server.js';
import App from './App.html';

polka() // You can also use Express
	.use(
		compression({ threshold: 0 }),
		serve('assets'),
		sapper({
			routes,
			App,
			store: request => {
				return new Store({
					version: 1,
					wifiSSIDs: request.session && request.session.wifiSSIDs ? request.session.wifiSSIDs : []
				});
			}
		})
	)
	.listen(process.env.PORT);

author(book) {
      return authors.find(author => author.id === book.author);
    }
  }
};

const server = new ApolloServer({ typeDefs, resolvers });

const app = express();
server.applyMiddleware({ app });

app
  .use(
    compression({ threshold: 0 }),
    sirv('assets'),
    sapper({
      routes,
      App,
      store: req => {
        const client = new ApolloClient({
          ssrMode: true,
          link: createHttpLink({
            uri: 'http://localhost:3000/graphql',
            credentials: 'same-origin',
            headers: {
              cookie: req.header('Cookie')
            }
          }),
          cache: new InMemoryCache()
        });
        const graphql = createProvider(client, { ssr: true });

import sapper from 'sapper'
import serve from 'serve-static'
import compression from 'compression'
import { Store } from 'svelte/store.js'
import { routes } from './manifest/server.js'
import App from './App.html'

dotenv.config()

const app = express()

app
  .use(
    compression({ threshold: 0 }),
    serve('assets'),
    sapper({
      App,
      routes,
      store: req => {
        return new Store({
          guide_contents: [],
        })
      },
    }),
  )
  .listen(process.env.PORT)