Modify the sentence-generator program of Case Study so that it inputs its vocabulary from a set of text files at startup. The filenames are nouns.txt, verbs. txt, articles.txt, and prepositions.txt.

(HINT: Define a single new function, getWords. This function should expect a filename as an argument. The function should open an input file with this name, define a temporary list, read words from the file, and add them to the list. The function should then convert the list to a tuple and return this tuple. Call the function with an actual filename to initialize each of the four variables for the vocabulary.)