It's just CSV.
The DNS from the datasets are not ordered consistently,
so we need to parse it completly.
It seems that converting to an IR before sending data to ./feed_dns.py
through a pipe is faster than decoding the JSON in ./feed_dns.py.
This will also reduce the storage of the resolved subdomains by
about 15% (compressed).
Mostly for performances reasons.
First one to implement threading later.
Second one to speed up the dichotomy,
but it doesn't seem that much better so far.