public function is($name, $value, $options = [], &$params = [])
    {
        $not = false;
        if (strncmp($name, 'not:', 4) === 0) {
            $name = substr($name, 4);
            $not = true;
        }
        $handlers = $this->get($name);
        $handlers = is_array($handlers) ? $handlers : [$handlers];
        $checker = $this->_classes['checker'];

        return $checker::check($value, $handlers, $options, $params) !== $not;
    }