树莓派python，tornado，返回json数据代码，初级网络编程。

import tornado.httpserverimport tornado.ioloopimport tornado.optionsimport tornado.webimport tornado.escapefrom tornado.options import define, optionsdefine("port", default=8002, help="run on the given port", type=int)class IndexHandler(tornado.web.RequestHandler):    def get(self):               greeting = self.get_argument('greeting', 'Hello')        respon = {'issuccess':greeting}          respon_json = tornado.escape.json_encode(respon)          self.write(respon_json)          #self.write(greeting + ', friendly user!')        if __name__ == "__main__":    tornado.options.parse_command_line()    app = tornado.web.Application(handlers=[(r"/", IndexHandler)])    http_server = tornado.httpserver.HTTPServer(app)    http_server.listen(options.port)    tornado.ioloop.IOLoop.instance().start()