docs: def register(self, models=None, wrapper_cls=None):
          """Registers with app_label.modelname, wrapper_cls.
          """
          self.loaded = True
          for model in models:
              model = model.lower()
              if model not in self.registry:
                  self.registry.update({model: wrapper_cls or self.wrapper_cls})
                  if self.register_historical:
                      historical_model = ".historical".join(model.split("."))
                      self.registry.update(
                          {historical_model: wrapper_cls or self.wrapper_cls}
                      )
              else:
                  raise AlreadyRegistered(f"Model is already registered. Got {model}.")