swagger is not a function error when using in fastify - fastify-swagger

Question

I'm trying to use fatify swagger in my fastify app and I was unable to start the application with the fastify swagger. i was getting the error. Please help me in resolving the error. Thanks in advance.
This is the error I'm getting when I'm running the app
fastify_app#1.0.0 start D:\dev\fastify_app
node app.js
{"level":30,"time":1666146720089,"pid":13484,"hostname":"Dell","msg":"Server listening at http://127.0.0.1:3000"}
{"level":30,"time":1666146720113,"pid":13484,"hostname":"Dell","msg":"Server listening at http://[::1]:3000"}
D:\dev\fastify_app\app.js:15
fastify.swagger()
^
TypeError: fastify.swagger is not a function
at D:\dev\fastify_app\app.js:15:15
at D:\dev\fastify_app\node_modules\fastify\lib\server.js:67:11
at Object.cb (D:\dev\fastify_app\node_modules\fastify\lib\server.js:128:15)
at Server.wrap (D:\dev\fastify_app\node_modules\fastify\lib\server.js:166:21)
at Object.onceWrapper (events.js:519:28)
at Server.emit (events.js:400:28)
at emitListeningNT (net.js:1365:10)
at processTicksAndRejections (internal/process/task_queues.js:81:21)
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! fastify_app#1.0.0 start: `node app.js`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the fastify_app#1.0.0 start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
npm ERR! A complete log of this run can be found in:
npm ERR! C:\Users\Dell\AppData\Roaming\npm-cache\_logs\2022-10-19T02_32_00_228Z-debug.log
This is my swagger.js file
const fastify = require("fastify")();
exports.options = fastify.register(require("#fastify/swagger"), {
routePrefix: "/docs",
exposeRoute: true,
swagger: {
info: {
title: "Fastify API",
description:
"Building a blazing fast REST API with Node.js, MongoDB, Fastify and Swagger",
version: "1.0.0",
},
externalDocs: {
url: "https://swagger.io",
description: "Find more info here",
},
host: "localhost:3000",
schemes: ["http"],
consumes: ["application/json"],
produces: ["application/json"],
},
});
This is my app.js code
const fastify = require("fastify")({logger:true});
require("dotenv").config();
const PORT = process.env.PORT;
fastify.register(require("./app/Routes/users.route"));
const swagger = require('./swagger')
fastify.get("/", (req, res) => {
res.send("Hello world");
});
const start = async () => {
try {
await fastify.listen({ port: PORT }, () => {
fastify.swagger()
console.log(`server is listening on port ${PORT}`);
});
} catch (error) {
console.log(error);
process.exit(1);
}
};
start();