public String[] unparse(LoadContext context, PaperInfo pi) {
   String info = pi.getPaperInfo(PaperInfo.BOTTOMMARGIN);
   if (info == null) {
     // Probably an error
     return null;
   }
   return new String[] {info};
 }
 @Override
 protected ParseResult parseNonEmptyToken(LoadContext context, PaperInfo pi, String value) {
   pi.setPaperInfo(PaperInfo.BOTTOMMARGIN, value);
   return ParseResult.SUCCESS;
 }