when creating new state, make it more convenient to add fields to the state. It's inconvenient now because you have to create a new state class.

[musslick]

Form John: This isn't possible using dataclasses as far as I know – you always have to create a new state class. What someone could do is implement the same logic but using a UserDict – they would have to work out how to translate what we've done for data classes so that it works on a dictionary, but that would be totally doable.

• [ ] first check if the state works with UserDict