The fitted_params method
A fitted_params method may be optionally overloaded. Its purpose is to provide MLJ access to a user-friendly representation of the learned parameters of the model (as opposed to the hyperparameters). They must be extractable from fitresult.
MMI.fitted_params(model::SomeSupervisedModel, fitresult) -> friendly_fitresult::NamedTupleFor a linear model, for example, one might declare something like friendly_fitresult=(coefs=[...], bias=...).
The fallback is to return (fitresult=fitresult,).