docs: def push(self, message, callback_arg=None):
          """message should be a dict recognized by the Stitch Import API.
  
          See https://www.stitchdata.com/docs/integrations/import-api.
          """
  
          if message['action'] == 'upsert':
              message.setdefault('key_names', self.key_names)
  
          message['client_id'] = self.client_id
          message.setdefault('table_name', self.table_name)
  
          self._add_message(message, callback_arg)
  
          batch = self._take_batch(self.target_messages_per_batch)
          if batch:
              self._send_batch(batch)