code: function (dateStyle, timeStyle, locale, timeZoneOffset) {
              locale = locale || defaultLocale;
              var datePattern = '';
              if (dateStyle !== undefined) {
                  datePattern = locale.datePatterns[dateStyle];
              }
              var timePattern = '';
              if (timeStyle !== undefined) {
                  timePattern = locale.timePatterns[timeStyle];
              }
              var pattern = datePattern;
              if (timePattern) {
                  if (datePattern) {
                      pattern = util.substitute(locale.dateTimePattern, {
                          date: datePattern,
                          time: timePattern
                      });
                  } else {
                      pattern = timePattern;
                  }
              }
              return new DateTimeFormat(pattern, locale, timeZoneOffset);
          }
docs: get a formatter instance of specified date style and time style.
  @param {KISSY.Date.Formatter.Style} dateStyle date format style
  @param {KISSY.Date.Formatter.Style} timeStyle time format style
  @param {Object} locale
  @param {Number} timeZoneOffset time zone offset by minutes
  @returns {KISSY.Date.Gregorian}
  @static