How to check whether user is logged into admin CP
 

Not sure if this is the right forum, I was wondering how to check (in code) whether a user is logged into the admin CP. I've already restricted viewing IP addresses to admins only, but for additional security I'd like to modify the postbit_ip template to only show the IP address if the admin has logged into the ACP. I suppose it would be something to do with checking for a cpsession row, but I was hoping there's some convenient function for this and I don't have to code it myself.