docs: protected ArrayDBIDs rowsBitsetToIDs(long[] rows) {
      ArrayModifiableDBIDs rowIDs = DBIDUtil.newArray(BitsUtil.cardinality(rows));
      DBIDArrayIter iter = this.rowIDs.iter();
      outer: for(int rlpos = 0; rlpos < rows.length; ++rlpos) {
        long rlong = rows[rlpos];
        // Fast skip blocks of 64 masked values.
        if(rlong == 0L) {
          iter.advance(Long.SIZE);
          continue;
        }
        for(int i = 0; i < Long.SIZE; ++i, rlong >>>= 1, iter.advance()) {
          if(!iter.valid()) {
            break outer;
          }
          if((rlong & 1L) == 1L) {
            rowIDs.add(iter);
          }
        }
      }
      return rowIDs;
    }