Can you help me with this Python Assignment?

Write a function cipher(plaintext, n) to shift all characters in a string of text. Your function should take 2 parameters, the plaintext to shift (a string) and the shift key n (an integer). Set up an accumulator variable (suggested name: ciphertext) in which to accumulate the result. Use a definite loop with the accumulator pattern to go through all characters in plaintext.

For each character, call your shift_char function to obtain the shifted version of that character, which you will concatenate into ciphertext. Return the ciphertext after the loop.

Here are some test cases:

>>> cipher('time', 4) 'xmqi' >>> cipher('welcome to the machine', 19) 'pxevhfx mh max ftvabgx' 

3. Suppose you have some ciphertext (i.e., 'iuet kag iqdq tqdq', or 'prqhb') but you dont know which decryption key (i.e., the number of characters to shift) to use. Write a function called codebreaker(ciphertext) that will try all possible Caesar cipher shifts (there are only 26 to try) and print out each possible deciphering. One of them will stand out as a valid English phrase. Your program must re-use your cipher function from question 2 above.