public Stream<Block> stream() {
        return streamBuffers()
                .map(serializer::makeBlock);
    }
@Test
    public void streamFirst100kCountTransactions() {
        File blockFile = new File(getClass().getResource("../core/first-100k-blocks.dat").getFile());
        BlockFileLoader loader = new BlockFileLoader(BitcoinNetwork.MAINNET, Collections.singletonList(blockFile));

        long transactionCount = loader.stream()
                .map(Block::getTransactions)
                .filter(Objects::nonNull)
                .mapToLong(Collection::size)
                .sum();

        assertEquals(446, transactionCount);
    }