In this exercise, if you do not know about it already, you will learn about the rotational cipher "ROT13".
A ROT13 on the Latin alphabet would be as follows:
- Plain: abcdefghijklmnopqrstuvwxyz
A ROT13 applied the Latin alphabet:
```
- Plain: abcdefghijklmnopqrstuvwxyz
||||||||||||||||||||||||||
- Cipher: nopqrstuvwxyzabcdefghijklm
```
Your purpose in this exercise is to create a similar `rotate` function that is a better version of the ROT13 cipher.
Your function will receive a `string` and a `number` and it will rotate each letter of that `string` by the `number` of times settled by the second argument towards the right, or towards the left if the number is negative.
Your `function` should only rotate letters. If the string includes punctuation and numbers
they will remain the same.
You will create a similar `rotate` function that is a better version of the ROT13 cipher.
### Notions
Your function will receive a `String` and an `i8`, and will rotate each letter of that string by the number of times described by the second argument. Positive numbers rotate to the right, negative numbers rotate to the left.