       let timeStringWithoutDashes = timeString.replacingOccurrences(of: ":", with: "")
       ISO8601Constants.dateFormatter.dateFormat = ISO8601Constants.HoursMinutesFormat
       
-      return ISO8601Constants.dateFormatter.date(from: timeStringWithoutDashes)!
+      return ISO8601Constants.dateFormatter.date(from: timeStringWithoutDashes)
     }
 
     // Time, with fractional seconds (e.g. 01:45:36.123).
     if let _ = timeString.range(of: ISO8601Constants.TimeWithFractionalSecondsRegexp, options: .regularExpression) {
       ISO8601Constants.dateFormatter.dateFormat = ISO8601Constants.TimeWithFractionalSecondsFormat
       
-      return ISO8601Constants.dateFormatter.date(from: timeString)!
+      return ISO8601Constants.dateFormatter.date(from: timeString)
     }
     
     // Time, with fractional seconds and time zone (e.g. 01:45:36.123+07:00).
     if let _ = timeString.range(of: ISO8601Constants.TimeWithFractionalSecondsAndTimeZoneRegexp, options: .regularExpression) {
       ISO8601Constants.dateFormatter.dateFormat = ISO8601Constants.TimeWithFractionalSecondsAndTimeZoneFormat
       
-      return ISO8601Constants.dateFormatter.date(from: timeString)!
+      return ISO8601Constants.dateFormatter.date(from: timeString)
     }
     
     return nil

      let dateStringWithoutDashes = dateString.replacingOccurrences(of: "-", with: "")
      ISO8601Constants.dateFormatter.dateFormat = ISO8601Constants.CalendarDateFormat
      
      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
