code: static Slice compactSlice(Slice slice, int index, int length)
      {
          if (slice.isCompact() && index == 0 && length == slice.length()) {
              return slice;
          }
          return Slices.copyOf(slice, index, length);
      }
docs: Returns a slice containing values in the specified range of the specified slice.
  If the range matches the entire slice, the input slice will be returned.
  Otherwise, a copy will be returned.