public function convert_date_to_iso8601($datestamp)
	{
		if (!preg_match('/\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}((\+|-)\d{2}:\d{2}|Z)/m', $datestamp))
		{
			return gmdate(self::DATE_FORMAT_ISO8601, strtotime($datestamp));
		}

		return $datestamp;
	}