code: T get(long index) {
          checkRange(index);
  
          if (checkSubRange(index)) {
              // cannot exceed Integer.MAX_VALUE (checked by checkSubRange)
              return subList.get((int) (index - subListOffset));
          }
          return null;
      }
docs: Gets the item at the index.
  
  @param index the request index
  @return the item