ExpressJS: normalizePort function is really necessary?

I used express-generator for a new project.

In file bin/www exists the function normalizePort:

...

var http_port = 3000;

var port = normalizePort(process.env.PORT || http_port);
app.set('port', port);

...

// Normalize a port into a number, string, or false.

function normalizePort(val) {
  var port = parseInt(val, 10);

  if (isNaN(port)) {
    // named pipe
    return val;
  }

  if (port >= 0) {
    // port number
    return port;
  }

  return false;
}

Question:

Is really necessary the function or I can will simply?

app.set('port', parseInt(process.env.PORT, 10));

The function is generic and avoid possibles errors?

I use dotenv and dotenv-safe module for load my file .env