Power Virtual Agents billed sessions analytics

Hi all,

I'm working on creating a report that would be incorporating some stats from our Power virtual agents chatbot. Most of what I need I got from the custom analytics git hub:  https://github.com/microsoft/PowerVirtualAgentsSamples/tree/master/CustomAnalytics

There is one bit of info that I don't see which is the billed sessions data.  I know that stat is on the analytics page on PVA web, but couldn't find the source of where that billed sessions comes from so I could pull that into my custom report.  

  Is there a different git hub project where I can get billed sessions included? or how to recreate this stat?

Thanks.