Swift Example Code

Just learning Swift and I noticed that Apple's example code on the Swift homepage does not compile in playground! I mean really, am I missing something?

https://developer.apple.com/swift/

extension String 
     { var banana : String 
          { let shortName = String(dropFirst(characters))
                return "\(self) \(self) Bo B\(shortName) Banana Fana Fo F\(shortName)" 
          } 
     } 
let bananaName = "Jimmy".banana

I changed line 03 to: { let shortName = String(dropFirst(self))

This seems to work. I tried to find feedback and let them know, but there seems to be no place for developers to provide simple feedback.