public function parse($rules): Rule\Set
    {
        $isArray = is_array($rules);
        $isAssoc = $isArray && self::isAssociative($rules);
        $set = null;
        if (is_string($rules) || is_object($rules) || $isAssoc) {
            $set = $this->getRule($rules);
        } elseif ($isArray) {
            foreach ($rules as $v) {
                $toAdd = $this->getRule($v);
                $set = $set === null ? $toAdd : $set->merge($toAdd);
            }
        }
        return $set ?? new Rule\Set();
    }