code: private static void maskInWord(int[] array, int index, int from, int to) {
      if (from == to) {
        return;
      }
  
      to = 32 - to;
      int word = wordAt(array, index);
      word |= ((0xffffffff >>> from) << (from + to)) >>> to;
      array[index] = word & WORD_MASK;
    }
docs: Sets all bits to true in a word within the given bit range.
  
  @param array The array.
  @param index The word index.
  @param from The lower bit index.
  @param to The upper bit index.