Comment by calineczka

Once upon a time I was working with a very challenging legacy code and I was building similar constructions in my mind. The office was sometimes noisy and chance of interruption was not that small. So I established a habit of writing kind of stack trace of my own thoughts so that I could easily come back to my state of mind after such thing. It looked like:

  There is a bug in module X
    Module is X is calling module Y when user is not yet activated
    We are creating user subscription
      We are using current subscription in subscription creation
        Current subscription is A when user is not activated
        Current subscription is B when user is activated
          Probably bug in method c()
            Think what is going to happen in situation M when changed the implementation to d().

The list sometimes had 12 elements that I was trying to fit in my head to find the solution to the problem. I now work remotely from home (quiet and all that) and most of the code that I work on is of much better quality (another company, better practices) but I still sometimes resort to this method when working on a complicated piece of code that is unfamiliar to me.