public function addFilter($filterName, $options = [])
    {
        // Create the filter hash so we can run multiple versions of the same filter
        $filterHash = sprintf('%s_%s', strtolower($filterName), md5(json_encode($options)));

        // Add the filter
        $this->options['filters'][$filterHash] = [
            'filter'  => strtolower($filterName),
            'options' => $options,
        ];

        unset($filterHash);

        return $this;
    }