public static function flexiDateTimeToDateTime($flexidatetime)
    {
        if (strchr($flexidatetime, '.')) { //NewFormat
            $format = self::$DateTimeFormat;
        } else { // Old format
            $format = 'Y-m-d\TH:i:s+P';
        }
        return \DateTime::createFromFormat($format, $flexidatetime);
    }