Part 0: Comparators, Treemaps, and Cities

For the first part of your project, you will implement a data dictionary that supports both city names and city coordinates as keys. You will also need to write an interpreter that will be able to handle basic XML commands. Your data dictionary can be written by merely playing games with comparators, thereby convincing a good old TreeMap or TreeSet to act like it's something else altogether.

Important: The only commands you must implement for part 0 are createCity, listCities, and clearAll.