I would like to get the opposite of a boolean value using dot syntax.

E.g.

```swift
let digitsExceptForFive = [1, 2, 3, 4, 6, 7, 8, 9]
let fives = [1, 2, 3, 4, 5, 6, 7, 8, 9].filter(!digitsExceptForFive.contains)
// Cannot convert value of type '(Int) -> Bool' to expected argument type 'Bool'

```

The following code works, however.

```swift
let digitsExceptForFive = [1, 2, 3, 4, 6, 7, 8, 9]
let notFives = [1, 2, 3, 4, 5, 6, 7, 8, 9].filter(digitsExceptForFive.contains)
// [1, 2, 3, 4, 6, 7, 8, 9]

```

I need to get the opposite value functionally using the not operator. If it's possible I would like not to have to define a bool extension or custom operator just to do so.

How can you do this in Swift?