code: public E lookahead(int position) {
          int idx = offset + position - 1;
          if (idx < elements.length) {
              return elements[idx];
          }
          return null;
      }
docs: Returns the element at the specified position
  in this stream without consuming it.
  
  @param position the position of the element to return
  @return the element at the specified position
  or {@code null} if no more elements left