code: public function paintPass($message)
      {
          parent::paintPass($message);
          $node    = new TreemapNode('Assertion', $message, true);
          $current = $this->_stack->peek();
          if ($current) {
              $current->putChild($node);
          } else {
              echo 'no current node';
          }
      }
docs: acceptor for passing assertion node