Creates a representer and updates the response body with the byte
        representation created for the given resource.

def _update_response_body(self, resource):
        """
        Creates a representer and updates the response body with the byte
        representation created for the given resource.
        """
        rpr = self._get_response_representer(resource)
        # Set content type and body of the response.
        self.request.response.content_type = \
                                rpr.content_type.mime_type_string
        rpr_body = rpr.to_bytes(resource)
        self.request.response.body = rpr_body