Rolling Cipher

Write a function that accepts a string and an n and returns a cipher by rolling each character forward (n > 0) or backward (n < 0) n times.

Note: Think of the letters as a connected loop, so rolling a backwards once will yield z, and rolling z forward once will yield a. If you roll 26 times in either direction, you should end up back where you started.

Examples

rolling_cipher("abcd", 1) ➞ "bcde"

rolling_cipher("abcd", -1) ➞ "zabc"

rolling_cipher("abcd", 3) ➞ "defg"

rolling_cipher("abcd", 26) ➞ "abcd"

Notes

• All letters are lower cased.
• No spacing.
• Each character is rotated the same number of times.