       let dateStringWithoutDashes = dateString.replacingOccurrences(of: "-", with: "")
       ISO8601Constants.dateFormatter.dateFormat = ISO8601Constants.CalendarDateFormat
       
-      return ISO8601Constants.dateFormatter.date(from: dateStringWithoutDashes)!
+      return ISO8601Constants.dateFormatter.date(from: dateStringWithoutDashes)
     }
     
     return nil

      let timeStringWithoutDashes = timeString.replacingOccurrences(of: ":", with: "")
      ISO8601Constants.dateFormatter.dateFormat = ISO8601Constants.HoursMinutesSecondsFormat

      return ISO8601Constants.dateFormatter.date(from: timeStringWithoutDashes)!
    }

    // Hours and minutes e.g. 10:10

      let dateStringWithoutDashes = dateString.replacingOccurrences(of: "-", with: "")
      ISO8601Constants.dateFormatter.dateFormat = ISO8601Constants.CalendarMonthFormat
      
      return ISO8601Constants.dateFormatter.date(from: dateStringWithoutDashes)
    }
    
    // Calender date e.g. 2016-01-21
