code: public static <T> T pickRandom (Iterator<T> iter, int count)
      {
          return pickRandom(iter, count, rand);
      }
docs: Picks a random object from the supplied iterator (which must iterate over exactly
  <code>count</code> objects.
  
  @return a randomly selected item.
  
  @exception NoSuchElementException thrown if the iterator provides fewer than
  <code>count</code> elements.