      *
      *  - returns: Representation of the date (self) in the specified format
      */
-    public func format(with dateFormat: String, timeZone: TimeZone) -> String? {
+    public func format(with dateFormat: String, timeZone: TimeZone) -> String {
         #if os(Linux)
             return format(with: dateFormat, timeZone: timeZone, locale: Locale.current)
         #else

     *
     *  - returns: Represenation of the date (self) in the specified format
     */
    public func format(with dateStyle: DateFormatter.Style, locale: Locale) -> String? {
        return format(with: dateStyle, timeZone: TimeZone.autoupdatingCurrent, locale: locale)
    }
    

     *
     *  - returns String? - Represenation of the date (self) in the specified format
     */
    public func format(with dateStyle: DateFormatter.Style, timeZone: TimeZone) -> String {
        #if os(Linux)
            return format(with: dateStyle, timeZone: timeZone, locale: Locale.current)
        #else
