code: def establish_connection(self):
          
          conninfo = self.connection
          if not conninfo.hostname:
              raise KeyError("Missing hostname for AMQP connection.")
          if conninfo.userid is None:
              raise KeyError("Missing user id for AMQP connection.")
          if conninfo.password is None:
              raise KeyError("Missing password for AMQP connection.")
          if not conninfo.port:
              conninfo.port = self.default_port
          return Connection(host=conninfo.host,
                            userid=conninfo.userid,
                            password=conninfo.password,
                            virtual_host=conninfo.virtual_host,
                            insist=conninfo.insist,
                            ssl=conninfo.ssl,
                            connect_timeout=conninfo.connect_timeout)
docs: Establish connection to the AMQP broker.