code: def unmount_process(self, process):
      
  
      # There is no remove_handlers, but .handlers is public so why not.  server.handlers is a list of
      # 2-tuples of the form (host_pattern, [list of RequestHandler]) objects.  We filter out all
      # handlers matching our process from the RequestHandler list for each host pattern.
      def nonmatching(handler):
        return 'process' not in handler.kwargs or handler.kwargs['process'] != process
  
      def filter_handlers(handlers):
        host_pattern, handlers = handlers
        return (host_pattern, list(filter(nonmatching, handlers)))
  
      self.app.handlers = [filter_handlers(handlers) for handlers in self.app.handlers]
docs: Unmount a process from the http server to stop receiving message
      callbacks.