I used console.log to display a port number but it not working.It displaying string but when i use this with value it not displaying.

```
const http = require('http');
const express = require('express');
const socketio = require('socket.io');

const PORT = process.env.PORT || 5000;

const app = express();
const server = http.createServer(app);
const io = socketio(server);

server.listen(PORT,()=>{
    return console.log('server has started on port ${PORT}');
});

```

I m getting Following:
Output:server has started on port ${PORT}