Quick

extend -> appendContentsOf

error: 'extend' has been renamed to 'appendContentsOf'
            examples.extend(group.examples)
                     ^~~~~~
                     appendContentsOf
Swift.RangeReplaceableCollectionType:3:17: note: 'extend' has been explicitly marked unavailable here
  mutating func extend<S : SequenceType where S.Generator.Element == Generator.Element>(newElements: S)
                ^