Redirect the login and register pages for logged in users to the account page

When logged in users visit the login or register page they will see a page that says "You are currently logged in as..." with some helpful links. This template can be customised, but for some these pages aren't necessary.

To redirect logged in users who visit the login or register pages to the account page, add this code to your theme's functions.php or to an mu-plugin file inside `wp-content/mu-plugins`: