code: public void excl(int x) {
          Assert.check(currentState != BitsState.UNKNOWN);
          Assert.check(x >= 0);
          sizeTo((x >>> wordshift) + 1);
          bits[x >>> wordshift] = bits[x >>> wordshift] &
              ~(1 << (x & wordmask));
          currentState = BitsState.NORMAL;
      }
docs: Exclude x from this set.