/**
  * {@inheritdoc}
  */
 public function wipe()
 {
     parent::wipe();
     $this->raw = '';
     if (file_exists($this->uri)) {
         drupal_unlink($this->uri);
     }
 }
 /**
  * {@inheritdoc}
  */
 public function wipe()
 {
     parent::wipe();
     dmemcache_delete($this->key, $this->bin);
 }