         let randomTimeInterval = NSTimeInterval(randomNumber(lowerBound: 0, upperBound: Int(timeIntervalSinceReferenceDate)))
         return referenceDate.dateByAddingTimeInterval(randomTimeInterval)
     }
+    
 }
+
+// MARK: - Private API
 
 extension Lorem {
     typealias Generator = (Void -> String)

//

import Foundation

func randomNumber(lowerBound: Int = 0, #upperBound: Int) -> Int {
    return lowerBound + Int(arc4random_uniform(UInt32(upperBound - lowerBound)))

    
    public class func sentence() -> String {
        let numberOfWordsInSentence: UInt = randomNumber(lowerBound: 4, upperBound: 16)
        let capitalizeFirstLetter: Decorator = { $0.stringByCapitalizingFirstLetter() }
        return compose(word, numberOfWordsInSentence, middleSeparator: " ", endSeparator: ".", decorator: capitalizeFirstLetter)
    }
    
