Magento 2.4 Admin Custom Controller Check If User Logged In and Redirect to Login If Not

In an Admin Controller Class, How do I check if the admin user is logged in, then redirect to the login page if not logged in, then return to the previous controller after login?

A cut down version of my script as follows.

use MagentoFrameworkViewResultPage;
use MagentoFrameworkControllerResultRedirect;

class Index implements HttpGetActionInterface

{
    /* Constructor */
  
    public function execute(): Page|Redirect
    {
        if (!$this->_isAllowed()) {
            ### How and where to redirect here? ###
        }

        /* Do stuff here and load Index page */
    }
}

Not sure if “$this->_isAllowed()” is the correct method to use to check if an admin user is logged in?

Not sure where/how to redirect if user not logged in, or session has ended.

Advice on the correct Magento way to do this would be appreciated.