Challenge 15 - Caesar's cipher
Julius Caesar protected his confidential information by encrypting it using a cipher. Caesar's cipher shifts each letter by a number of letters. If the shift takes you past the end of the alphabet, just rotate back to the front of the alphabet. In the case of a rotation by 3, w, x, y and z would map to z, a, b and c.
Create a function that takes a string s (text to be encrypted) and an integer k (the rotation factor). It should return an encrypted string.
String:
Factor:
Output: