Add 2 FA login to existing code easy 1hr project

There is already register and login routes in below link just add otp route and it's authentication to existing project on github
Link =>
https://github.com/bradtraversy/node_passport_login

Now do it as early as possible it will take just less than half hour
Build a simple good looking 2 Factor authentication Login Web App with a single user session at any given point in time

It should have the following flows

Login flow - enter an email, and it will send a 4 digit numerical code to that email
Enter the 4 digit code on the web app and it will validate the login and allow entry to another page that says " Thank you for logging in" and keep the session alive
3. Single User Session : This app should allow only a single user session at one time - i.e. if a user with a specific email id is already logged in with an email and 4 digit code, and if someone tries to enter the same email elsewhere (another browser like firefox, opera, bing) then they (2nd user) should get a message that the someone else (1st user) is logged in and they (second user) can show a button (Log out other User) and on click log the other user out