docs: def register_extension_class(ext, base, *args, **kwargs):
      """Instantiate the given extension class and register as a public attribute of the given base.
  
      README: The expected protocol here is to instantiate the given extension and pass the base
      object as the first positional argument, then unpack args and kwargs as additional arguments to
      the extension's constructor.
      """
      ext_instance = ext.plugin(base, *args, **kwargs)
      setattr(base, ext.name.lstrip('_'), ext_instance)