code: def post_receive(self) -> None:
          
          from federation.utils.activitypub import retrieve_and_parse_profile  # Circulars
          try:
              from federation.utils.django import get_function_from_config
          except ImportError:
              logger.warning("ActivitypubFollow.post_receive - Unable to send automatic Accept back, only supported on "
                             "Django currently")
              return
          get_private_key_function = get_function_from_config("get_private_key_function")
          key = get_private_key_function(self.target_id)
          if not key:
              logger.warning("ActivitypubFollow.post_receive - Failed to send automatic Accept back: could not find "
                             "profile to sign it with")
              return
          accept = ActivitypubAccept(
              activity_id=f"{self.target_id}#accept-{uuid.uuid4()}",
              actor_id=self.target_id,
              target_id=self.activity_id,
          )
          try:
              profile = retrieve_and_parse_profile(self.actor_id)
          except Exception:
              profile = None
          if not profile:
              logger.warning("ActivitypubFollow.post_receive - Failed to fetch remote profile for sending back Accept")
              return
          try:
              handle_send(
                  accept,
                  UserType(id=self.target_id, private_key=key),
                  recipients=[{
                      "fid": profile.inboxes["private"],
                      "protocol": "activitypub",
                      "public": False,
                  }],
              )
          except Exception:
              logger.exception("ActivitypubFollow.post_receive - Failed to send Accept back")
docs: Post receive hook - send back follow ack.