public function start($name = null): self
    {
        if (null !== $name) {
            $this->items[$name] = clone $this->items[self::BASE_ITEM];
            $this->activeItems[$name] = $item = $this->items[$name] ?? new Item($name);
            $item->start($name);

            return $this;
        }

        $this->activeItems[self::BASE_ITEM] = $item = $this->items[self::BASE_ITEM];
        $item->start(self::BASE_ITEM);

        return $this;
    }