code: public void set(int bitIndex) {
  		if (bitIndex < 0)
  			throw new IndexOutOfBoundsException("bitIndex < 0: " + bitIndex);
  
  		int wordIndex = wordIndex(bitIndex);
  		expandTo(wordIndex);
  
  		words[wordIndex] |= (1L << bitIndex); // Restores invariants
  
  		checkInvariants();
  	}
docs: Sets the bit at the specified index to <code>true</code>.
  
  @param     bitIndex   a bit index.
  @exception IndexOutOfBoundsException if the specified index is negative.
  @since     JDK1.0