/**
  * Returns the stored name for a $taxonomy and $taxonomy_slug if exists in cache
  * 
  * @param string  $taxonomy  Taxonomy to use
  * @param string  $taxonomy_slug  Taxonomy slug to look up
  * @return string
  */
 public static function getTaxonomyName($taxonomy, $taxonomy_slug)
 {
     return Helper::pick(ContentService::getTaxonomyName($taxonomy, $taxonomy_slug), $taxonomy_slug);
 }