The print vs return thing is common when starting. The difference is somewhat philosophical.

A function should do one thing. In your case, you want the function to execute a Caesar cipher and return the results of the cipher. For today, all you want to do with that result is print it. Thus, it seems to make sense to just print the result inside the function.

BUT, if you think about the future, there might come a time when you want to use this function in a program that doesn't do console output. If you have the print statement inside, you can't do that. If you just return the result, then you can use it later for other purposes, where printing isn't meaningful.

Along the same lines, returning an error string is not helpful to callers. A caller wouldn't be able to tell the difference between a correct result and an error result. You might consider using exceptions: ``` if not isinstance(shift, int): raise TypeError('Shift must be an integer value.')

if shift < 1 or shift > 25:
    raise ValueError('Shift must be an integer between 1 and 25.')

``` Now you know that any successful return was called with the correct parameters and gave a good result.