Swift/Xcode: Need to create the following in a playground on Xcode.

Create a function, called check, that takes in an Int and returns an optional String.

The input parameter should be called value.

If the passed in argument is negative or zero, return nil.

Else return a string version of the argument.

Example:

let numberString1: String? = check(value: 10) // numberString should be "10"

let numberString2: String? = check(value: 0) // numberString should be nil

let numberString3: String? = check(value: -2) // numberString should be nil