Method unlock

/**
 * Unlock cached item
 *
 * @param   string  $id     The cache data ID
 * @param   string  $group  The cache data group
 *
 * @return  boolean
 *
 * @since   3.0.0
 */
public function unlock($id, $group = null)
{
    $cache_id = $this->_getCacheId($id, $group) . '_lock';
    return static::$_db->delete($cache_id);
}