/**
  * Enter description here...
  *
  * @param <type> $key
  * @param <type> $value
  */
 public function data($key, $value = null)
 {
     if (!isset($value)) {
         // TODO? implement specific jQuery behavior od returning parent values
         // is child which we look up doesn't exist
         return phpQuery::data($this->get(0), $key, $value, $this->getDocumentID());
     } else {
         foreach ($this as $node) {
             phpQuery::data($node, $key, $value, $this->getDocumentID());
         }
         return $this;
     }
 }