code: public void addAll(IntBitSet set) {
          int i;
  
          if (set.data.length > data.length) {
              resize(set.data.length);
          }
  
          for (i = 0; i < set.data.length; i++) {
              data[i] |= set.data[i];
          }
      }
docs: Computes the union. The result is stored in this set.
  @param   set   the set to be combined with