Непонимание асинхронности, motor, tornado

class MessagesHandler(tornado.web.RequestHandler):
    @tornado.web.asynchronous
    def get(self):
        """Display all messages"""
        self.write('<a href="/compose">Compose a message</a><br>')
        self.write('<ul>')
        ldb = self.settings['db']
        (ldb.messages.find()
        .sort([('_id', -1)])
        .to_list(callback=self._got_messages, length=10))

    def _got_messages(self, messages, error):
        if error:
            raise tornado.web.HTTPError(500, error)
        elif messages:
            self.write(messages_template.generate(messages=messages))
        self.finish()