How to use the lsst.afw.cameraGeom package?

Hi! I need to transform the coordinates in pixels in a detector into focal plane coordinates in mm. This because I have done statics on PSF in a certain point of the calexp.image and I would like to report this in the focal plane coordinate system. I have found here that lsst.afw.cameraGeom.detector.transform method should be able to do what I need, but I am not used to python and I am struggling in reaching my objective.
Is it also possible to get the full transformation of a grid of corresponding pixels in different detectors to focal plane coordinates throught a full camera transformation map?
I have also found that the examples link in the same page has been deleted from the github (section basic usage), while some test files are now available. These are beautiful, but not fully compatible with a python new user.
Could you please give me the exact command to use to retrieve these information or point me to some notebooks where these methods are used?
Thank you a lot.
PS: I would also like to be able to retrieve the camera rotation angle (or the coordinates in the OCS system)

Thanks for your question, Laura! We are looking into this, and will get back to you shortly.

Thank you! I have found how to do thanks to Jim Chiang that provided me a small function with an example of the call to the method I needed!
Anyway, if you have some notebook available on this packege, I would be happy to have it! Thanks again!