docs: public double getWeight(int i)
      {
          if(i >= size() || i < 0)
              throw new IndexOutOfBoundsException("Dataset has only " + size() + " members, can't access index " + i );
          
          if(weights == null)
              return 1;
          else if(weights.length <= i)
              return 1;
          else return weights[i];
      }