class_docstr: Manages interactions between agents on messenger as well as direct interactions
  between agents and the messenger overworld.
code: def _handle_webhook_event(self, event):
      if "message" in event:
          if (
              "image_url" in event and event["image_url"] is not None
          ) or (
              "attachment_url" in event
              and event["attachment_url"] is not None
          ):
              event["message"]["image"] = True
          self._on_new_message(event)
      elif "delivery" in event:
          self.confirm_message_delivery(event)
      elif "read" in event:
          self.handle_message_read(event)
  
imports: import logging
  import os
  from parlai.core.agents import create_agent
  import parlai.chat_service.utils.logging
  import parlai.chat_service.utils.server
  from parlai.utils.io import PathManager
  from parlai.chat_service.services.messenger.agents import MessengerAgent
  from parlai.chat_service.core.socket import ChatServiceMessageSocket
  from parlai.chat_service.services.messenger.message_sender import MessageSender
  from parlai.chat_service.core.chat_service_manager import ChatServiceManager
label_desc: Use image node_id 11 for calling the MessengerManager obj's underlying member method code with example usage: obj._handle_webhook_event(event) without return types