public function filterByFixed($fixed = null, $comparison = null)
    {
        if (is_string($fixed)) {
            $fixed = in_array(strtolower($fixed), array('false', 'off', '-', 'no', 'n', '0', '')) ? false : true;
        }

        return $this->addUsingAlias(ObjectTableMap::COL_FIXED, $fixed, $comparison);
    }