public function dropTags($tag = null) { $isnull = $tag === null; if (!$tag instanceof Model_Tag) { if (is_array($tag) or $tag instanceof Model_List_Tag) { foreach ($tag as $item) { $this->removeTag($item); } return true; } else { $tag = new Model_Tag($this->_db, $tag); } } return $tag->untagModel($this, $isnull); }