protected function getFixedHuffmanTrees()
    {
        return [
            HuffmanTree::createFromLengths(array_merge(
                array_fill_keys(range(0, 143), 8),
                array_fill_keys(range(144, 255), 9),
                array_fill_keys(range(256, 279), 7),
                array_fill_keys(range(280, 287), 8)
            )),
            HuffmanTree::createFromLengths(array_fill_keys(range(0, 31), 5))
        ];
    }