sample code to generate OTP on nodejs

vdocipherNode.js

/// this is the backend code. Use the generated OTP in this file to embed videos using embed code as given on 
/// https://www.vdocipher.com/page/api.curl

let request = require('request');

var api_url = "https://api.vdocipher.com/v2/";
var secret_key = "API_SECRET_KEY";

function getOtp(v, c) {
	request.post({
		url: api_url + "otp",
		qs: {
			video : v
		},
		form: {
			clientSecretKey : secret_key
		}
	}, function(error, response, body){
		if (error){
			c(response.statusCode);
			return false;
		}
		if (response.statusCode !== 200) {
			c(response.statusCode);
			return false;
		}
		c(null, JSON.parse(body));
	});
}


var res = getOtp("VIDEO_ID", function(error, data) {
	console.log(data.otp);
});

How about the annotation , how can we add it ?
Thanks