The file a1_exercises.py is a starting template. Edit this file to develop your solutions for Part 1. The file test_functions.py contains a few simple tests that will help you in debugging your solutions. To run the tests, in bash or other Linux environment, type:

python -m unittest test_functions.py

def is_triple(n):
    """Return True if n is a multiple of 3; False otherwise."""
    pass

def last_prime(m):
    """Return the largest prime number p that is less than or equal to m.
    You might wish to define a helper function for this.
    You may assume m is a positive integer."""
    pass

def quadratic_roots(a, b, c):
    """Return the roots of a quadratic equation (real cases only).
    Return results in tuple-of-floats form, e.g., (-7.0, 3.0)
    Return "complex" if real roots do not exist."""
    pass

def new_quadratic_function(a, b, c):
    """Create and return a new, anonymous function (for example
    using a lambda expression) that takes one argument x and 
    returns the value of ax^2 + bx + c."""
    pass

def perfect_shuffle(even_list):
    """Assume even_list is a list of an even number of elements.
    Return a new list that is the perfect-shuffle of the input.
    For example, [0, 1, 2, 3, 4, 5, 6, 7] => [0, 4, 1, 5, 2, 6, 3, 7]"""
    pass

def list_of_3_times_elts_plus_1(input_list):
    """Assume a list of numbers is input. Using a list comprehension,
    return a new list in which each input element has been multiplied
    by 3 and then has 1 added to it."""
    pass

def triple_vowels(text):
    """Return a new version of text, with all the vowels tripled.
    For example:  "The *BIG BAD* wolf!" => "Theee *BIIIG BAAAD* wooolf!".
    For this exercise assume the vowels are 
    the characters A,E,I,O, and U (and a,e,i,o, and u).
    Maintain the case of the characters."""
    pass

def count_words(text):
    """Return a dictionary having the words in the text as keys,
    and the numbers of occurrences of the words as values.
    Assume a word is a substring of letters and digits and the characters
    '-', '+', *', '/', '@', '#', '%', and "'" separated by whitespace,
    newlines, and/or punctuation (characters like . , ; ! ? & ( ) [ ] { } | : ).
    Convert all the letters to lower-case before the counting."""
    pass

Here, you will work with existing code to complete a program that can perform a simple type of generative AI. It will generate text strings in the style of short text messages. It will use a simple and small language model. The model consists of some lists of words and a probabilistic context-free grammar.

An example of a message is

  "slowly avoided crazy boss lol. boss ranted omg."

You are given 3 files:

  generate.py
  vocabulary.py
  grammar.py

You'll make the following modifications to these files.

• generate.py:
  Fill in the missing code in the two incomplete functions: gen_text and gen_overall_message. Then test your code by executing on the command line:

     python generate.py
  

  Debug as needed, so that the program generates random text messages based on the original vocabulary.
  
• vocabulary.py:
  Change the word list for NOUN to a list of breeds of dogs and cats, plus a few items relevant to them. The first word in the list must be "husky".
  Add a new word list ANIMAL_SOUND and give it 5 to 10 members. The first item in this list must be "arf".
  
• grammar.py:
  Add a new rule for EVENT that allows an ANIMAL_SOUND to be part of the event description. Put this rule after the other EVENT-headed rules.

If you need to add any other new word lists to vocabulary.py, you may do this, and if you need to add any additional rules to grammar.py to make your adjusted generation program work better, you may do this. However, the first rule in each existing group should remain as the first rule in the group, and the first word in each existing word list remains the first, so that with CHOICE_MODE equal to "first" in generate.py, the output of the program is not affected by your changes to grammar.py and vocabulary.py.

Turn in your updated three files as part of the overall assignment.

1. Q. Will we be graded on style?
   A. See the above.
2. Q. When I submit my code, will additional test cases be run on my functions, other than those distributed with the starter code?
   A. In general, yes. Also, you are encouraged to develop test cases of your own, to help you debug your code's behavior on possible edge cases.