private static final String trimTrailingCommas(String s) {
            return s.replaceAll(",+$", "");
        }
Create and return a Format based on the format string from a cell's style. If the pattern cannot be parsed,
return a default pattern.

@param cell The Excel cell
@return A Format representing the excel format. May return null.
fastexcel-test/src/test/java/cn/idev/excel/test/temp/dataformat/DataFormatter1.java