I am aware that an argument passed to a function will be seen as "val", even if the variable was initialized as "var". But this has been a problem for me. In this example code below, I want to modify the value of variable "num" by using the function "changeNum". But of course, Kotlin won't allow me to modify it. How do I get around this? How can I use the function "changeNum" to modify the variable "num"?

```
fun main() {
    var num: Int = 5
    changeNum(num)
}

fun changeNum(num: Int){
    num += 2
    print(num)
}

```