code: static Optional<DistributerException> checkCode(Code code, String format, Object...args) {
          if (code != Code.OK) {
              KeeperException kex = KeeperException.create(code);
              return Optional.of(loggedDistributerException(kex, format, args));
          } else {
              return Optional.absent();
          }
      }
docs: Boiler plate method that checks a zookeeper callback @{link {@link KeeperException.Code},
  converts it to a {@link DistributerException} and if it does not indicate success,
  
  @param code a {@link KeeperException.Code callback code}
  @param format {@link String#format(String, Object...) compliant format string
  @param args formatter arguments
  @return an {@link Optional} that may contain a {@link DistributerException}