public void AndNot(BitSet bs) {
if (bs == null) {
throw new ArgumentNullException("bs");
}
Int32 i = Math.Min(this._bits.Length, bs._bits.Length);
while (--i >= 0) {
this._bits[i] &= ~bs._bits[i];
}
this.RecalculateWordsInUse();
this.CheckInvariants();
}