You asked your team to collect the serial numbers of all your equipment for insurance purposes. Unfortunately some members of the team visited the same rooms and you are certain that some of the lists they sent in contain the same serial numbers. Assuming you have three text files of serial numbers named "serials-andy", "serials-mary", and "serials-pat", how would you remove all the duplicate serial numbers? (You can verify your answer by creating three files with these names, puting some random numbers in them with some duplicates, and trying the commands)