The given code snippet suggests that it's part of a...

The given code snippet suggests that it's part of a server setup in JavaScript, potentially using the Node.js framework. Here's what it does, piece by piece:

1. .listen(...):
   This is a method found in server frameworks like Node.js's built-in http module or libraries like Express (app.listen) to start the server and have it listen for incoming connections on a specified port.

2. +PORT:
   The unary + operator converts PORT to a number (if it isn't already). This is often used to ensure that values that might be strings (e.g., environment variables) are coerced to a proper number.

3. +PORT + 1:
   This takes the numeric value of PORT, adds 1 to it, and uses it as the port number for the server to listen on. The result is that the server will start on a port one higher than the given PORT value.

4. () => {:
   This begins an arrow function, which is a callback that will be executed once the server successfully starts and begins listening. Whatever functionality should run after the server starts would be defined within this arrow function.

Example Explanation:

If this line is part of a Node.js application and PORT equals 3000, then the server will listen on port 3001 (3000 + 1). When the server successfully starts listening, the provided arrow function (() => { ... }) will run, which is often used to log a message like "Server is running on port ..." to the console.

Example Full Code Context:

const express = require('express');
const app = express();
const PORT = process.env.PORT || 3000;

app.listen(+PORT + 1, () => {
  console.log(`Server is running on port ${+PORT + 1}`);
});

In this case, if PORT is 3000, the server starts on 3001, and the console logs:
Server is running on port 3001.

Let me know if further clarification is needed!