How do I check my sp_Blitz/sp_WhoIsActive versions across multiple servers/databases?

I have a bunch of SQL Servers registered within my SSMS, lots of different SQL versions, editions and DB compatibilities. I want to check out if **any** of those servers have **any** of the [sp_Blitz](https://github.com/BrentOzarULTD/SQL-Server-First-Responder-Kit) or [sp_WhoIsActive](http://whoisactive.com) stored procedures installed, and which versions they are. I know I can **right-click** on my **Registered Servers group** and open **one** query window that connects to **all** the servers in the group, but is there a reliable way to check which SProcs and versions I have?