A type that explicitly supplies its own playground Quick Look.
Swift Standard Library
The CustomPlaygroundQuickLookable protocol is deprecated, and will be removed from the standard library in a future Swift release. To customize the logging of your type in a playground, conform to the CustomPlaygroundDisplayConvertible protocol.
If you need to provide a customized playground representation in Swift 4.0 or Swift 3.2 or earlier, use a conditional compilation block: