code: public Object previous() {
          Object element = null;
          if (previousElement != null) {
              element = previousElement;
              previousElement = null;
          } else {
              element = getPreviousElement();
              if (element == null) {
                  throw new java.util.NoSuchElementException();
              }
          }
          return element;
      }
docs: * Returns the previous element of primary key collection.
  
  @return