let numbers = [1, 2, 3, 4, 5]
func addOne(numbers: [Int]) -> [Int] {
    var modifiedNumbers = [Int]()
    for number in numbers {
        modifiedNumbers.append(number + 1)
    }
    return modifiedNumbers
}
print(addOne(numbers: numbers))
//RESULT: [2, 3, 4, 5, 6]