integrate Apollo graphQL into express

var express = require('express')
const  { ApolloServer,gql } = require('apollo-server-express');

const typeDefs = gql`
type Query {
 greet: String,
 users :[User],
 musers:[User]
}

type User {
    id:String,
    email:String,
    password:String,
    companyId:String
}`

const resolvers = {
  Query: {
    greet: () => {
      return "Hello from GraphQl side"
    },
    users:()=>{
        return fetchData()
    }
   },
}


const app = express();

const SERVER = new ApolloServer({
    typeDefs: typeDefs,
    resolvers: resolvers,
    playground: {
      endpoint: `http://localhost:3600/graphql`,
      settings: {
        'editor.theme': 'light'
      }
    }
  });

  SERVER.applyMiddleware({
    app: app
  });

app.listen(3600 , ()=> {console.log("App started")})


var  fetchData = ()=>{

    var fakeUsers =  [
        {
          "id": "BJrp-DudG",
          "email": "alice@facegle.io",
          "password": "alice123",
          "companyId": "HJRa-DOuG"
        },
        {
          "id": "ry9pbwdOz",
          "email": "bob@goobook.co",
          "password": "bob123",
          "companyId": "SJV0-wdOM"
        }
      ]
    return fakeUsers;
   
    }