Right, but my point is that you are still guarding a calculation, there. I suppose it is fair to say that this code just describes the paying for it side of things. My point is that I often want the code to describe everything I can actively do while the machine is in use by someone else.
To that end, if I was to "script out" a trip to the laundry mat, it would not be as simple as "reserve both, when successful, pay." It would be "Confirm driers are working, find an empty washer to fill, if found fill it if not check times and plan to come back later if above a threshold start over when I'm back, otherwise pay it, come back later when it is it done, ...."
To that end, if I was to "script out" a trip to the laundry mat, it would not be as simple as "reserve both, when successful, pay." It would be "Confirm driers are working, find an empty washer to fill, if found fill it if not check times and plan to come back later if above a threshold start over when I'm back, otherwise pay it, come back later when it is it done, ...."