Before you use a plugin, you have to know all but one of the following. which one is it?
the html that it requires
the css that it provides
the methods that it provides
the options that it provides

Description: write function lastfirst() that takes one argument—a list of strings of the format "lastname, firstname" —and returns a list consisting of two lists: (a) a list of all the last names (b) a list of all the first names