nspl\ds\Set::union PHP Метод

    public function union($sequence)
    {
        if ($sequence instanceof Set) {
            $result = new Set();
            $result->array = $this->array + $sequence->array;
            return $result;
        }
        args\expects(args\traversable, $sequence);
        $result = $this->copy();
        foreach ($sequence as $element) {
            $result->array[static::getElementKey($element)] = $element;
        }
        return $result;
    }