Get a mapping class for this model

        This method will return a Mapping class for your model, generating it using settings from a
        `Mapping` class on your model (if one exists). The generated class is cached on the manager.

def mapping(self):
        """Get a mapping class for this model

        This method will return a Mapping class for your model, generating it using settings from a
        `Mapping` class on your model (if one exists). The generated class is cached on the manager.
        """
        if not hasattr(self, "_mapping"):
            if hasattr(self.model, "Mapping"):
                mapping_klass = type("Mapping", (DjangoMapping, self.model.Mapping), {})
            else:
                mapping_klass = get_first_mapping(self.model)
                if mapping_klass is None:
                    mapping_klass = DjangoMapping
            self._mapping = mapping_klass(self.model)
        return self._mapping