createDictLetterFrequencies that reads the file and also takes a parameter n. This method should return a dictionary of dictionaries. The outer dictionary associates the previous n letters of a word with an inner dictionary, which indicates the frequency at which the next letter appears based on those previous n letters. <"ing", <"a", 0.2> <"c", 0.1> <"l", 0.5> <"y", 0.2> >