/**
  * @param BlockNode $node
  *
  * @return string
  */
 protected function printBlockNode(BlockNode $node)
 {
     $childNodes = $node->getChildNodes();
     if ($node->isSubPattern()) {
         $output = '';
         foreach ($childNodes as $childNode) {
             $output .= $this->printNode($childNode);
         }
         return $output;
     }
     return $this->printNode($childNodes[mt_rand(0, count($childNodes) - 1)]);
 }