AoC 2020 - Day 4: Passport Processing

This time, I used pydantic a lot.
The entire exercise here was about data validation, and this is an area where pydantic really shy.
Actually, I started with simple dataclasses, but soon the lack of validation there led me to the full pydantic.
A small problem blocked me for long – I had to solve the first exercise in a different way, just to debug it: as a legacy from using dataclass, I was still assigning str(value) to a non-nullable string field; and that was enough to skip the validation. The field was None, but for some reason that was not detected.

Overall, an easy one – but I could have done much quicker if I had used pydantic from the beginning, and strictly followed its approach.