docs: public boolean and(BitArray other)
      {
          if (bits != other.bits)
          {
              throw new IllegalArgumentException("number of bits differ");
          }
          int l = bits/8;
          for (int ii=0;ii<l;ii++)
          {
              if ((array[ii] & other.array[ii]) != 0)
              {
                  return true;
              }
          }
          for (int ii=l*8;ii<bits;ii++)
          {
              if (isSet(ii) && other.isSet(ii))
              {
                  return true;
              }
          }
          return false;
      }