         }
         self.bytes = bytes
     }
-    
+
     /// Initialize UUID from string
     ///
     /// - parameter string: string in default UUID representation

                      let c2 = characters.popFirst() else {
                        return nil
                }
                
                let c = UInt8("\(c1)\(c2)", radix: 16)!
                
                self.bytes[byte] = c
                byte++
            }
        }
        
        if byte != 16 {
            return nil
        }


/// Printable UUID
extension UUID4: CustomStringConvertible {

    /// "Human readable" version of the UUID
    public var description: String {
        return "\(bytes[0].hexString())\(bytes[1].hexString())\(bytes[2].hexString())\(bytes[3].hexString())-\(bytes[4].hexString())\(bytes[5].hexString())-\(bytes[6].hexString())\(bytes[7].hexString())-\(bytes[8].hexString())\(bytes[9].hexString())-\(bytes[10].hexString())\(bytes[11].hexString())\(bytes[12].hexString())\(bytes[13].hexString())\(bytes[14].hexString())\(bytes[15].hexString())".uppercaseString
