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

        return $this->addUsingAlias(MediaTableMap::COL_KNOWN, $known, $comparison);
    }