code: def serve():
      
      logging.getLogger().setLevel(logging.DEBUG)
      logging.info('Python Tornado Crossdock Server Starting ...')
  
      tracer = Tracer(
          service_name='python',
          reporter=NullReporter(),
          sampler=ConstSampler(decision=True))
      opentracing.tracer = tracer
  
      tchannel = TChannel(name='python', hostport=':%d' % DEFAULT_SERVER_PORT,
                          trace=True)
      register_tchannel_handlers(tchannel=tchannel)
      tchannel.listen()
  
      app = tornado.web.Application(debug=True)
      register_http_handlers(app)
      app.listen(DEFAULT_CLIENT_PORT)
  
      tornado.ioloop.IOLoop.current().start()
docs: main entry point