/**
  * Verifies if a reference is already defined in registry
  *
  * @param   string  $reference  The reference to search
  *
  * @return  bool
  */
 public function has($reference)
 {
     return $this->dom_ids->has($reference);
 }
 /**
  * Tests if an index is cached
  *
  * @param string $index
  * @return bool
  */
 public function isCached($index)
 {
     return $this->_cache->has($index);
 }