docs: def listen(self):
          """Self-host using 'bind' and 'port' from the WSGI config group."""
  
          msgtmpl = (u'Serving on host %(host)s:%(port)s')
          host = CONF.wsgi.wsgi_host
          port = CONF.wsgi.wsgi_port
          LOG.info(msgtmpl,
                   {'host': host, 'port': port})
          server_cls = self._get_server_cls(host)
          httpd = simple_server.make_server(host,
                                            port,
                                            self.app,
                                            server_cls)
          httpd.serve_forever()