docs: private static ArrayContainer arrayContainerOf(final int from, final int to,
        final int cardinality, final long[] words) {
      // precondition: cardinality is max 4096
      final short[] content = new short[cardinality];
      int index = 0;
  
      for (int i = from, socket = 0; i < to; ++i, socket += Long.SIZE) {
        long word = words[i];
        while (word != 0) {
          long t = word & -word;
          content[index++] = (short) (socket + Long.bitCount(t - 1));
          word ^= t;
        }
      }
      return new ArrayContainer(content);
    }