code: async def controller(self):
          
          return await Connection.connect(
              self.endpoint,
              username=self.username,
              password=self.password,
              cacert=self.cacert,
              bakery_client=self.bakery_client,
              loop=self.loop,
              max_frame_size=self.max_frame_size,
          )
docs: Return a Connection to the controller at self.endpoint