docs: def filter(self, object, *args, **kw):
      '''
      Identical to `PluginSet.handle`, except:
  
      #. If this plugin set is empty, `object` is returned as-is.
      #. If any plugin returns ``None``, it is returned without
         calling any further plugins.
      '''
      for plugin in self.plugins:
        object = plugin.handle(object, *args, **kw)
        if object is None:
          return object
      return object