The goal of this exercise is to write a cyclic cipher to encrypt messages. This type of cipher was used by Julius Caesar to communicate with his generals. It is very simple to generate but it can actually be easily broken and does not provide the security one would hope for. The key idea behind the Caesar cipher is to replace each letter by a letter some fixed number of positions down the alphabet. For example, if we want to create a cipher shifting by 3, you will get the following mapping: Plain: ABCDEFGHIJKLMNOPQRSTUVWXYZ Cipher: DEFGHIJKLMNOPQRSTUVWXYZABC To be able to generate the cipher above, we need to understand a little bit about how text is represented inside the computer. Each character has a numerical value and one of the standard encodings is ASCII (American Standard Code for Information Interchange). It is a mapping between the numerical value and the character graphic. For example, the ASCII value of 'A' is 65 and the ASCII value of 'a' is 97. To convert between the ASCII code and the character value in Python, you can use the following code, also remember that python stores strings in Unicode: letter = 'a' #converts a letter to ascii code ascii.code = ord(letter) #converts ascii code to a letter letter ses = shi(ascii.code) print ascii. code, letter les Create a file called cipher.py. Start your program by asking the user for a phrase to encode and the shift value. Then begin the structure of your program by entering in this loop: encoded phrass = for c in phrase: encoded phrase = encoded phrase + c Hint: Note that the ASCII value of 'A' is 65 and 'a' is 97, not 0. So you will have to think how to use the modulus operator to achieve the desired result. Apply the cipher separately to the upper and lower case letters. Here is what you program should output: Enter sentence to encrypt: Mayday! Mayday! Enter shift value: 4 The encoded phrase is: Qeshec! Qeshes! When you are done, print a copy of the file and turn it in