/**
  * Removes a single tag
  *
  * @param $tagName string
  */
 private function removeTag($tagName)
 {
     $tagName = trim($tagName);
     $normalizer = $this->namespace . '\\TaggingUtil::slug';
     $tagSlug = call_user_func($normalizer, $tagName);
     if ($count = $this->tagged()->where('tag_slug', '=', $tagSlug)->delete()) {
         TaggingUtil::decrementCount($tagName, $tagSlug, $count);
     }
 }