code: def register_url(url, handler, name=None, kwargs=None):
      
      if name is None and kwargs is None:
          app_config.urls.append((url, handler))
          return
  
      if name is None:
          app_config.urls.append((url, handler, kwargs))
          return
  
      app_config.urls.append((url, handler, kwargs, name))
docs: insert url into tornado application handlers group
  
      :arg str url: url
      :handler object handler: url mapping handler
      :name reverse url name
      :kwargs dict tornado handler initlize args