Session04 Tasks

Task 1 - Dictionaries and Sets
Task 2 - Trigrams
Task 3 - Wrapper Function
Task 4 - Mailroom Madness
It's generally not a good idea to make a recursive call to a function inside a `while` loop in that function's definition. It causes the creation of a new execution frame and effectively negates the purpose of a `while` loop. It would be better to allow this loop back to the top and reprompt the user for input. You'll need to change the `while` loop's conditional statement for this to work. Consider `while True` with `break` statements when you want to exit.