I disliked that they don't explain the logic in the ```arrivals()``` function, but it is because in a uniform distribution from 0 to 1 (which is what ```random(

I disliked that they don't explain the logic in the ```arrivals()``` function, but it is because in a uniform distribution from 0 to 1 (which is what ```random()``` is), the probability that a value falls below 1/6 is exactly 1/6, i.e.: P(random() < 1/6) ~= 1/6 . Which is how they simulate a dice landing a "6". This explanation could be included in the text.