I'm working on a python program for homework and the problem asks me to develop a program that encrypts a message using a caesar cipher. I need to be able to have the user input a number to shift the encryption by, such as 4: e.g. 'A' to 'E'. The user also needs to input the string to be translated. The book says to use a zip() to do the problem. I am confused on how I would do this though.

I have this but it doesn't do anything

>>>def ceasarCipher(string, shift):
    strings = ['abc', 'def']
    shifts = [2,3]
    for string, shift in zip(strings, shifts):

        print ceasarCipher(string,shift)


>>>string = 'hello world'
>>>shift = 1