For this exercise a function will be tested **with the exam own main**. However the student **still needs** to submit a structured program:
This means that:
- The package needs to be named `package main`.
- The submitted code needs one declared function main(```func main()```) even if empty.
- The function main declared needs to **also pass** the `Restrictions Checker`(illegal functions tester). It is advised for the student to just empty the function main after its own testings are done.
- Every other rules are obviously the same than for a `program`.
### Instructions
Write a function that:
- converts an `int` value to a `string` using the specified base in the argument
- and that returns this `string`
The base is expressed as an `int`, from 2 to 16. The characters comprising
the base are the digits from 0 to 9, followed by uppercase letters from A to F.
For example, the base `4` would be the equivalent of "0123" and the base `16` would be the equivalent of "0123456789ABCDEF".
If the value is negative, the resulting `string` has to be preceded with a
