code: def _update_kind_map(cls):
      
      cls._kind_map[cls._class_name()] = cls
      class_key = cls._class_key()
      if class_key:
        cls._class_map[tuple(class_key)] = cls
docs: Override; called by Model._fix_up_properties().
  
      Update the kind map as well as the class map, except for PolyModel
      itself (its class key is empty).  Note that the kind map will
      contain entries for all classes in a PolyModel hierarchy; they all
      have the same kind, but different class names.  PolyModel class
      names, like regular Model class names, must be globally unique.