In the book "Learning Swift" (Wagner) there's this example about the closures ( closures as parameters in particular):

```
func firstInNumbers(numbers: [Int], passingTest: (number: Int) -> Bool -> Int? {

for number in numbers {
   if passingTest(number: number) {
       return number
     }
  }
return nil
}

let numbers = [1,2,3,4,5] 
func greaterThanThree(number: Int) -> Bool {
    return number > 3
}
var firstNumber = firstInNumbers(numbers, greaterThanThree)
println(firstNumber)

<code>

```

So, why the (number: number) syntax in the if statement ?