Thanks for taking the time to reply.

The take home exercise is here: https://github.com/mjb8086/checkout-kata/tree/main

I'd also created an launched an iPhone app in the meantime, and had an idea for another where I could write the backend in Python3/FastAPI.

Also, I mistyped, the book C# book I am reading is "C# In Depth", not "C# in a Nutshell". The former has details on the new language features of each version, when they'd be best used, etc