This method is used to defer the construction of the final url in
        the case that the Api is created with a Blueprint.

        :param url_part: The part of the url the endpoint is registered with
        :param registration_prefix: The part of the url contributed by the
            blueprint.  Generally speaking, BlueprintSetupState.url_prefix

def _complete_url(self, url_part, registration_prefix):
        """This method is used to defer the construction of the final url in
        the case that the Api is created with a Blueprint.

        :param url_part: The part of the url the endpoint is registered with
        :param registration_prefix: The part of the url contributed by the
            blueprint.  Generally speaking, BlueprintSetupState.url_prefix
        """
        parts = {
            'b': registration_prefix,
            'a': self.prefix,
            'e': url_part
        }
        return ''.join(parts[key] for key in self.url_part_order if parts[key])