1 (defun memq (item x)
2   (cond ((null x) nil)
3 	((eql item (car x)) x)
4 	(t (memq item (cdr x)))))
5 
6 (defun equal? (la lb)
7   (cond
8     ((and (symbolp la) (symbolp lb))
9      (eql la lb))
10     ((symbolp la) (symbolp lb))
11     ((symbolp lb) (symbolp la))
12     ((null la) (null lb))
13     ((null lb) (null la))
14     (t (and
15 	(equal? (car la) (car lb))
16 	(equal? (cdr la) (cdr lb))))))