GoPiGo3-ROS - Orientation of the Ydlidar

Having some problems getting SLAM to work I noticed something interesting. I think that the tf for the Lidar is wrong, by 90degrees around the z-axis. And this matches some of the pictures in the book where it looks like it’s mounted 90degrees off.

Is this true? Why was it mounted that way? And save me a bunch of trial and error to find where that static tf is stored and how to change it? Thanks!

Perhaps @brjapon is the best source on this one.

(Must either have to have read the book or integrated a Lidar to know what a “static tf” is. Having not done either, its a new term to me.)