`(,(normalize (car prog)) ,(normalize (cadr prog))) ; (f a)
`(,(list (normalize (car prog)) (normalize (cadr prog)))
,(normalize (caddr prog))))) ; (f a b)
`(,(normalize (car prog)) ,(normalize (cadr prog))) ; (f a)
`(,(list (normalize (car prog)) (normalize (cadr prog)))
,(normalize (caddr prog))))) ; (f a b)