public function instantiate($identifier, $config = array())
    {
        //Get the filter(s) we need to create
        $filters = (array) $identifier;

        //Create the filter chain
        $filter = array_shift($filters);
        $filter = $this->_createFilter($filter, $config);

        foreach ($filters as $name) {
            $filter->addFilter(self::_createFilter($name, $config));
        }

        return $filter;
    }