I6 call to an object's routine not working

I am making a class that switches between container and supporter, for curiosity reasons. The code itself works, but the compiler tells me

The code is this [code]Class Switcher
with
switch [; if (self has container){ give self ~container; give self supporter;} else { give self ~supporter; give self container;};]
has
container open openable ,
;

Switcher Box_thing “Box thing” test_room
with
name
“box” “thing” ,
description “A simple test of a class.”,
react_before [ ; Jump: self.switch; print "You switch the ", (the) self, “.”; ; rtrue; ];[/code]

Try self.switch(); instead.

That worked. thanks.