code: public static <T> KeyRange<T> open(final T start, final T stop) {
      return new KeyRange<>(KeyRangeType.FORWARD_OPEN, start, stop);
    }
docs: Create a {@link KeyRangeType#FORWARD_OPEN} range.
  
  @param <T>   buffer type
  @param start start key (required)
  @param stop  stop key (required)
  @return a key range (never null)