Ruby & Friends

We will try Mob Programming with one or two nice Advent of Code exercises. I've only read the TL;DR of mob programming, so what I mean is this:

• I will have prepared my computer with an empty repo and some tools (Ruby 2.7 & RSpec).
• My screen will be displayed for everybody.
• I will sit at the keyboard but I will only type code that other people tell me.
• I might pause (i.e., stop typing what you tell me) to ask for clarifications or protest if I think we are not solving the right problem.