code: def setup(self):
          
          self.pre_handlers = pre_handlers = {}
          self.post_handlers = post_handlers = {}
          for name in sorted(vars(type(self))):
              if name.startswith('init_'):
                  getattr(self, name)()
              elif name.startswith('pre_'):
                  pre_handlers[name[4:]] = getattr(self, name)
              elif name.startswith('post_'):
                  post_handlers[name[5:]] = getattr(self, name)
docs: All the node-specific handlers are setup at
          object initialization time.