Creates a representer for the given combination of resource and
        content type. This will also find representer factories that were
        registered for a base class of the given resource.

def create(self, resource_class, content_type):
        """
        Creates a representer for the given combination of resource and
        content type. This will also find representer factories that were
        registered for a base class of the given resource.
        """
        rpr_fac = self.__find_representer_factory(resource_class,
                                                  content_type)
        if rpr_fac is None:
            # Register a representer with default configuration on the fly
            # and look again.
            self.register(resource_class, content_type)
            rpr_fac = self.__find_representer_factory(resource_class,
                                                      content_type)
        return rpr_fac(resource_class)