; (expression expected-result): expected results are data.
('hello hello)
('(a (b) . c) (a (b) . c))
((if nil 'wrong 'right) right)
((join 'a 'b) (a . b))
((apply join '(a b)) (a . b))
((car saved) left)
; Observe identity inside Bel; printing alone cannot distinguish pair sharing.
((id saved saved) t)
((id saved (join 'left '(right))) nil)
((xar saved 'changed) changed)
(saved (changed right))