code: public void clear(int index) {
          if(index < 0 || index >= size)
              throw new IndexOutOfBoundsException("index: " + index);
  
          int wordIndex=wordIndex(index);
          words[wordIndex]&=~(1L << index);
      }
docs: Sets the bit specified by the index to {@code false}.
  @param index the index of the bit to be cleared.
  @throws IndexOutOfBoundsException if the specified index is negative.