/**
  * Unset tag used
  *
  * @param string    $targetId target id
  * @param TagEntity $tag      tag object
  * @return void
  */
 protected function unused($targetId, TagEntity $tag)
 {
     if ($this->repo->existsUsed($targetId, $tag) === true) {
         $this->repo->deleteUsed($targetId, $tag);
         $this->repo->decrement($tag);
     }
 }