; a. Return T if a list has an even number of elements on the first level, and
;    NIL otherwise, without counting the elements of the list

(defun noEven (l)
    (prog ((x t))
     here
        (cond
            ((null l) (setq x t) (return x))
            ((null (cdr l)) (setq x nil)  (return x))
            (t (setq l (cddr l)))
        )
        (go here)
    )
)

; b. Check whether a linear list is a set

(defun isSet (l)
    (prog ((x t))
     there
        (cond
            ((null l) (setq x t) (return x))
            ((member (car l) (cdr l)) (setq x nil)  (return x))
            (t (setq l (cdr l)))
        )
        (go there)
    )
)