old_contents: '''Echo HTTP handler'''
  import tornado.gen
  import tornado.web
  
  
  class EchoHandler(tornado.web.RequestHandler):  # pylint: disable=R0904
      '''Handle echo operations'''
  
      @tornado.gen.coroutine
      @tornado.web.asynchronous
      def post(self):
          '''POST method'''
  
          message = self.request.body.decode('utf-8')
  
          self.set_status(200)
          self.write('msg:' + message)
          self.finish()
  
new_contents: '''Echo HTTP handler'''
  import tornado.gen
  import tornado.web
  
  
  class EchoHandler(tornado.web.RequestHandler):  # pylint: disable=R0904
      '''Handle echo operations'''
  
      @tornado.gen.coroutine
      @tornado.web.asynchronous
      def post(self):
          '''POST method'''
  
          message = self.request.body.decode('utf-8')
  
          self.set_status(200)
          self.write('You sent me:' + message)
          self.finish()
  
subject: change response message