Creates a new representer for the given resource class.

        The representer obtains a reference to the (freshly created or looked
        up) mapping for the resource class.

def create_from_resource_class(cls, resource_class):
        """
        Creates a new representer for the given resource class.

        The representer obtains a reference to the (freshly created or looked
        up) mapping for the resource class.
        """
        mp_reg = get_mapping_registry(cls.content_type)
        mp = mp_reg.find_or_create_mapping(resource_class)
        return cls(resource_class, mp)