PrimaryKeyCreator, no parameter are passed to the create_pk method

I want to make an MurmurHash class to create a primary key for a new model instance.
I did this class that adheres to the PrimaryKeyCreator protocol:

# https://github.com/hajimes/mmh3
import mmh3

class Mmh3PrimaryKey:
    """
    A client-side generated primary key that follows the MurmurHash (MurmurHash3) spec.
    https://en.wikipedia.org/wiki/MurmurHash
    """

    @staticmethod
    def create_pk(self, *args, **kwargs) -> str:
        return str('some argument in args / kwargs')

and set Meta primary_key_creator_cls like this:

class ErrorServer(HashModel):
    local_hostname: str
    class Meta:
        primary_key_creator_cls = Mmh3PrimaryKey

But when I instantiate ErrorServerclass, no parameter (len of *args, **kwargs == 0) are passed to create_pk

es = ErrorServer(local_hostname='my_hostname', param2='Test')

Start by reading the PrimaryKeyCreator protocol in aredis_om/model/model.py around line 856 and the primary_key_creator_cls documentation in docs/models.md. Trace model instantiation for ErrorServer and verify whether constructor values reach create_pk; done means the documented creator receives the expected arguments, with coverage for the reported instantiation.