Write an event-driven version of the checker simulation. Make sure it produces the same results as the time-driven simulation in the chapter.

Suppose our retail store is going to upgrade from one to two checkers. Either we can have a single line with the person at the front of the line going to whichever checker is free (similar to airline check-in and some banks) or we can have two separate lines where we assume that arriving customers will queue up in the shortest line. Write a simulation to determine if there is any significant advantage to one approach over the other in terms of the average waiting time for the customers.