Excercise for the Language Processor example

For the material covered today (based on Sections 2.6 and 6.3), I'm assigning one problem that is based on "Project 2.B" on pag 91 in the book, but adapted to how the example was modified for class. Enter this into the automated grading system as "6.3.x".

6.3.x. Following the pattern for makeInterrogative, write a function makeImperative and appropriate helper functions that transforms and prints the sentence into the imperative mood. The verb should be in an appropriate place, and the subject should be vocative (basically, replace the article with "O"). For example, the sentence "the big dog quickly chased a red ball through the bright field" would be transformed into "chase a red ball quickly through the bright field, o big dog!".

A few details to note:

• When making strings, your code should have straight up-and-down quotes like ", not slanted quotes like “ and ”. If the editor you're using automatically makes quotes slanted (often called "smart quotes"), you'll need to turn it off. Let me know if you need help with that. For example, here are instructions about how to disable smart quotes for recent versions of MacOS.
• The order that the words and phrases appear counts. In particular, note that the adverb (if any) should appear before the prepositional phrase (if any), as in the example given. (This is kind of arbitrary, but the grading system needs to expect something or another...)
• As usual, to test your code in the interpreter, you'll need to put all the supporting datatypes and functions (the code from class starting with (* "Feature presentation" begins here *)), but not when submitting your solution. On the other hand, when you submit, don't forget to include the helper functions that you wrote or completed, namely imperativeT(), imperativeI(), imperativeL(), and printVocative() in addition to, of course, the function makeImperative().
• Although getting the spacing and punctuation right is a good idea, your submitted code will not be tested on that. The grading system will accept code that produces strings with extra or missing spaces and punctuation.