public function setBlacklist($blacklist)
    {
        if (is_array($blacklist)) {
            $this->blacklist = array_map('strval', $blacklist);
        } elseif ($blacklist instanceof \ArrayObject && true) {
            $this->blacklist = array_map('strval', $blacklist->getArrayCopy());
        } elseif (is_string($blacklist)) {
            $this->blacklist = [];
            for ($i = 0; $i < strlen($blacklist); $i++) {
                $this->blacklist[] = $blacklist[$i];
            }
        } else {
            throw new \Exception('Incorrect blacklist given. Allowed blacklist are: string, array or ArrayObject.');
        }
    }