- Write a function that given a string transforms all numeric digits using the ROT5 cipher.
- Everything that is not a numeric digit should be unchanged.
- Examples: 0 -> 5, 1 -> 6, 2 -> 7, ... , 8 -> 3, 9 -> 4
- Hint: If you run ROT5 twice, you should end up where you started.
- The FOCUS for this Kata is to make it automatically testable, in whatever way that seems suitable to you.
- If you want an extra challenge you could apply ROT13 for the letters A-Z, making rot13("DECERNO") => "QRPREAB" and rot13(rot13("DECERNO")) => "DECERNO".