docs: async def _send_typing(self, request: Request, stack: Stack):
          """
          Send to Facebook typing indications
          """
  
          active = stack.get_layer(lyr.Typing).active
  
          msg = ujson.dumps({
              'recipient': {
                  'id': request.conversation.fbid,
              },
              'sender_action': 'typing_on' if active else 'typing_off',
          })
  
          headers = {
              'content-type': 'application/json',
          }
  
          params = {
              'access_token': self._access_token(request),
          }
  
          post = self.session.post(
              MESSAGES_ENDPOINT,
              params=params,
              data=msg,
              headers=headers,
          )
  
          logger.debug('Sending: %s', msg)
  
          async with post as r:
              await self._handle_fb_response(r)