We mentioned that the choice of red and blue as colors may not be a good one, as some people have a rare form of color blindness that makes these 2 colors appear similar. Also, displaying colors on overhead projectors and other devices can give very different results than on computer screens. As a result, we may want to change the colors for the 2 different types of cars. What are better colors to use? Change the code in this case study so that the R user can specify different colors to represent the horizontal and vertical moving cars. Make certain that all of the code still yields the same results! In how many places does the caller have to specify the new colors? Ideally, they should only have to specify it in one place and the rest of the code should know which colors correspond to horizontal and vertical. How do we implement this?