code: void and(LongBitSet other) {
  		int pos = Math.min(numWords, other.numWords);
  		while (--pos >= 0) {
  			bits[pos] &= other.bits[pos];
  		}
  		if (numWords > other.numWords) {
  			Arrays.fill(bits, other.numWords, numWords, 0L);
  		}
  	}
docs: this = this AND other