protected function colorArgs($args)
    {
        if ($args[0] != 'list' || count($args[2]) < 2) {
            return array(array('color', 0, 0, 0), 0);
        }
        list($color, $delta) = $args[2];
        $color = $this->assertColor($color);
        $delta = floatval($delta[1]);

        return array($color, $delta);
    }