`Handler` can probably benefit from making it an abstract class conxtructed by a metaclass, not a `namedtuple`

[KOLANICH]

So you will be able to specify the interface and maybe reuse some code.

A metaclass can do the work on autoregistration in into the registry.

[pombredanne]

I am open to a better design. Would you be willing to help? What would it look like in particular?

[KOLANICH]

Something like https://github.com/UniGrammar/UniGrammarRuntime.py/blob/master/UniGrammarRuntime/IParsingBackend.py#L11-L24