code: def serialize(self):
      msg = {
          "msg_type": self.msg_type,
          "payload": self.payload,
      }
      return json.dumps(msg) + "\n"
  
file_path: metaflow/metaflow/sidecar/sidecar_messages.py
imports: import json
label_desc: Use image node_id 2 for calling the Message obj's underlying member method code with example usage: obj.serialize() and returns: unknown