[C++-sig] boost python doc problem? (return_self)

[Neal Becker]

The example in ref man for return_self, shows:
   class_<widget>("Widget")
      .def("sensitive", &Widget::get_sensitive)
      .def("sensitive", &Widget::set_sensitive, return_self<>())
      ;

But Widget::set_sensitive is void, it doesn't return anything.  What am I
missing here?